A urine test strip or dipstick is a basic

diagnostic Diagnosis is the identification of the nature and cause of a certain phenomenon. Diagnosis is used in many different disciplines, with variations in the use of logic, analytics, and experience, to determine "cause and effect". In systems enginee ...

tool used to determine

pathological Pathology is the study of the causes and effects of disease or injury. The word ''pathology'' also refers to the study of disease in general, incorporating a wide range of biology research fields and medical practices. However, when used in th ...

changes in a patient's

urine Urine is a liquid by-product of metabolism in humans and in many other animals. Urine flows from the kidneys through the ureters to the urinary bladder. Urination results in urine being excreted from the body through the urethra. Cellul ...

in standard

urinalysis Urinalysis, a portmanteau of the words ''urine'' and ''analysis'', is a panel of medical tests that includes physical (macroscopic) examination of the urine, chemical evaluation using urine test strips, and microscopic examination. Macroscopic e ...

. A standard urine test strip may comprise up to 10 different chemical pads or

reagents In chemistry, a reagent ( ) or analytical reagent is a substance or compound added to a system to cause a chemical reaction, or test if one occurs. The terms ''reactant'' and ''reagent'' are often used interchangeably, but reactant specifies a ...

which

react REACT or React may refer to: Science and technology * REACT (telescope), a telescope at Fenton Hill Observatory, New Mexico, US Computing * React (JavaScript library) , a JavaScript library for building user interfaces, from Facebook ** React Nat ...

(change color) when immersed in, and then removed from, a urine sample. The test can often be read in as little as 60 to 120 seconds after dipping, although certain tests require longer. Routine testing of the urine with multiparameter strips is the first step in the diagnosis of a wide range of diseases. The analysis includes testing for the presence of

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...

glucose Glucose is a simple sugar with the molecular formula . Glucose is overall the most abundant monosaccharide, a subcategory of carbohydrates. Glucose is mainly made by plants and most algae during photosynthesis from water and carbon dioxide, u ...

ketone In organic chemistry, a ketone is a functional group with the structure R–C(=O)–R', where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group –C(=O)– (which contains a carbon-oxygen double b ...

s, haemoglobin,

bilirubin Bilirubin (BR) ( Latin for "red bile") is a red-orange compound that occurs in the normal catabolic pathway that breaks down heme in vertebrates. This catabolism is a necessary process in the body's clearance of waste products that arise from t ...

urobilinogen Urobilinogen is a colorless by-product of bilirubin reduction. It is formed in the intestines by bacterial action on bilirubin. About half of the urobilinogen formed is reabsorbed and taken up via the portal vein to the liver, enters circulation an ...

acetone Acetone (2-propanone or dimethyl ketone), is an organic compound with the formula . It is the simplest and smallest ketone (). It is a colorless, highly volatile and flammable liquid with a characteristic pungent odour. Acetone is miscibl ...

nitrite The nitrite ion has the chemical formula . Nitrite (mostly sodium nitrite) is widely used throughout chemical and pharmaceutical industries. The nitrite anion is a pervasive intermediate in the nitrogen cycle in nature. The name nitrite also ...

and

leucocyte White blood cells, also called leukocytes or leucocytes, are the cells of the immune system that are involved in protecting the body against both infectious disease and foreign invaders. All white blood cells are produced and derived from multi ...

s as well as testing of pH and

specific gravity Relative density, or specific gravity, is the ratio of the density (mass of a unit volume) of a substance to the density of a given reference material. Specific gravity for liquids is nearly always measured with respect to water at its dens ...

or to test for infection by different pathogens. The test strips consist of a ribbon made of

plastic Plastics are a wide range of synthetic or semi-synthetic materials that use polymers as a main ingredient. Their plasticity makes it possible for plastics to be moulded, extruded or pressed into solid objects of various shapes. This adapta ...

paper Paper is a thin sheet material produced by mechanically or chemically processing cellulose fibres derived from wood, rags, grasses or other vegetable sources in water, draining the water through fine mesh leaving the fibre evenly distribu ...

of about 5

millimetre 330px, Different lengths as in respect to the electromagnetic spectrum, measured by the metre and its derived scales. The microwave is between 1 meter to 1 millimeter. The millimetre (American and British English spelling differences#-re, -er, ...

wide, plastic strips have pads impregnated with chemicals that react with the compounds present in urine producing a characteristic colour. For the paper strips the reactants are absorbed directly onto the paper. Paper strips are often specific to a single reaction (e.g. pH measurement), while the strips with pads allow several determinations simultaneously. There are strips which serve different purposes, such as qualitative strips that only determine if the sample is positive or negative, or there are semi-quantitative ones that in addition to providing a positive or negative reaction also provide an estimation of a quantitative result, in the latter the colour reactions are approximately proportional to the concentration of the substance being tested for in the sample. The reading of the results is carried out by comparing the pad colours with a colour scale provided by the manufacturer, no additional equipment is needed. This type of analysis is very common in the control and monitoring of diabetic patients. The time taken for the appearance of the test results on the strip can vary from a few minutes after the test to 30

minute The minute is a unit of time usually equal to (the first sexagesimal fraction) of an hour, or 60 seconds. In the UTC time standard, a minute on rare occasions has 61 seconds, a consequence of leap seconds (there is a provision to insert a neg ...

s after immersion of the strip in the urine (depending on the brand of product being used). Semi-quantitative values are usually reported as: trace, 1+, 2+, 3+ and 4+; although tests can also be estimated as milligrams per decilitre. Automated readers of test strips also provide results using units from the

International System of Units The International System of Units, known by the international abbreviation SI in all languages and sometimes pleonastically as the SI system, is the modern form of the metric system and the world's most widely used system of measurement. ...

Test method

The test method consists of immersing the test strip completely in a well mixed sample of urine for a short period of time, then extracting it from the container and supporting the edge of the strip over the mouth of the container to remove excess urine. The strip is then left to stand for the time necessary for the reactions to occur (usually 1 to 2 minutes), and finally the colours that appear are compared against the chromatic scale provided by the manufacturer. An improper technique can produce false results, for example, leukocytes and erythrocytes precipitate at the bottom of the container and may not be detected if the sample is not properly mixed, and in the same way, if an excess of urine remains on the strip after it has been removed from the test sample, may cause the reagents to leak from the pads onto adjacent pads resulting in mixing and distortion of the colours. To ensure that this does not occur it is recommended the edges of the strip are dried on absorbent paper.

Reactions for generalised tests

pH

The lungs and kidneys are the main regulators of an organism's acid / alkali balance. The balance is maintained through the controlled excretion of acidic hydrogens in the form of

ammonia Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogenous ...

ions, monohydrogenated

phosphate In chemistry, a phosphate is an anion, salt, functional group or ester derived from a phosphoric acid. It most commonly means orthophosphate, a derivative of orthophosphoric acid . The phosphate or orthophosphate ion is derived from phosph ...

, weak organic acids and through the reabsorption of

bicarbonate In inorganic chemistry, bicarbonate (IUPAC-recommended nomenclature: hydrogencarbonate) is an intermediate form in the deprotonation of carbonic acid. It is a polyatomic anion with the chemical formula . Bicarbonate serves a crucial biochemi ...

through glomerular filtration in the convoluted tubules of the nephron. The pH of urine normally vary between 4.5 and 8 with the first urine produced in the morning generally being more acidic and the urine produced after meals generally more alkaline. Normal reference values are not provided for urine pH as the variation is too wide and results have to be considered in the context of the other quantifiable parameters. The determination of urinary pH has two main objectives, one is diagnostic and the other is therapeutic. On the one hand it provides information regarding the balance between acid and alkali in a patient and allows identification of the substances that are present in the urine in crystalline form. On the other hand, certain illnesses require a patient to keep the pH of their urine within given narrow margins, whether to promote the elimination of chemotherapeutic agents, avoid the precipitation of salts that promote the formation of kidney stones, or in order to facilitate the control of a urinary infection. Regulating diet mainly controls urinary pH, although using medication can also control it. Diets rich in animal proteins tend to produce acidic urine, while diets mainly composed of vegetables tend to produce alkali urine. Commercial brands measure pH in increments of 0.5 or 1 pH units between pH 5 and 9. In order to differentiate pH in this wide range it is common to use a double

indicator Indicator may refer to: Biology * Environmental indicator of environmental health (pressures, conditions and responses) * Ecological indicator of ecosystem health (ecological processes) * Health indicator, which is used to describe the health o ...

system comprising methyl red and bromothymol blue.ADW Diabetes.
/ref> Methyl red produces a colour change from red to yellow in the range of pH 4 to 6 and the bromothymol blue changes from yellow to blue between pH 6 and 9. In the range 5 to 9 the strips show colours that change from orange at pH 5, passing through yellow and green to dark blue at pH 9.Bayer Multistix reagent strips
/ref>

Specific gravity

One of the kidneys’ important functions is to reabsorb water after glomerular filtration. The complex process of reabsorption is usually one of the first renal functions to be affected by disease. The specific gravity of urine is a measure of its density compared to H₂O and depends on the quantity and density of solutes (molecules with more mass per volume increase measure of specific gravity). The measurement of specific gravity should not be confused with the measurement of

osmotic concentration Osmotic concentration, formerly known as osmolarity, is the measure of solute concentration, defined as the number of osmoles (Osm) of solute per litre (L) of solution (osmol/L or Osm/L). The osmolarity of a solution is usually expressed as Osm/L ...

, which is more related to the number of particles than with their mass. The urine test strip test for specific gravity is based on the change in dissociation constant (pK_a) of an anionic polyelectrolyte (poly-(methyl vinyl ether/maleic anhydride)) in an alkali medium that is ionised and releases hydrogen ions in proportion to the number of cations present in the solution. The greater the cation concentration of the urine the more hydrogen ions are released, thereby reducing the pH. The pad also includes bromothymol blue, which measures this change in pH. It should be remembered that the test strip only measures cation concentration, it is therefore possible that urine with a high concentration of non-ionic solutes (such as glucose or urea) or with high molecular weight compounds (such as the media used to provide radiographic contrast) will yield a result that will be erroneously lower than that measured by densitometry. The colours vary from dark blue with a reading of 1.000 to yellow for a reading of 1.030. # In an alkaline medium

Polyelectrolyte-H_n + Cationsⁿ⁺ → Polyelectrolyte-Cations + nH⁺

# In an alkaline medium

H⁺ + Bromothymol blue_(Blue) → Bromothymol blue-H⁺_(Yellow)

Elevated protein concentrations produce slightly elevated specific density results as a consequence of the indicator's protein error; in addition, samples with a pH above 6.5 give lower readings as a result of the indicator's bias. For this reason the manufacturers recommend that 5 units are added to the specific gravity reading when the pH is greater than 6.5.

Blood

Blood may be present in the urine either in the form of intact red blood cells (hematuria) or as the product of red blood cell destruction, hemoglobin (hemoglobinuria). Blood present in large quantities can be detected visually. Hematuria produces cloudy red urine, and hemoglobinuria appears as a clear red specimen. Any amount of blood greater than five cells per microliter of urine is considered clinically significant; visual examination cannot be relied upon to detect the presence of blood. Microscopic examination of the urinary sediment shows intact red blood cells, but free hemoglobin produced either by hemolytic disorders or lysis of red blood cells is not detected. Therefore, chemical tests for hemoglobin provide the most accurate mean for determining the presence of blood. Once blood has been detected, the microscopic examination can be used to differentiate between hematuria and hemoglobinuria. Chemical tests for blood use the pseudoperoxidase activity of hemoglobin to catalyze a reaction between the heme component of both hemoglobin and myoglobin and the chromogen (a substance that acquires colour after a chemical reaction) tetramethylbenzidine to produce an oxidized chromogen, which has a green-blue colour. Reagent strip manufacturers incorporate peroxide, and tetramethylbenzidine, into the blood testing area. Two colour charts are provided that correspond to the reactions that occur with hemoglobinuria, myoglobinuria and hematuria (RBCs). In the presence of free hemoglobin/myoglobin, uniform colour ranging from a negative yellow through green to a strongly positive green-blue appears on the pad. In contrast, intact red blood cells are lysed when they come in contact with the pad, and the liberated hemoglobin produces an isolated reaction that results in a speckled pattern on the pad. Reagent strip tests can detect concentrations as low as five red blood cells per microliter; however, care must be taken when comparing these figures with the actual microscopic values, because the absorbent nature of the pad attracts some of urine. The terms trace, small, moderate, and large (or trace, 1+, 2+, and 3+) are used for reporting. False-positive reactions due to menstrual contamination may be seen. They also occur if strong oxidizing detergents are present in the specimen container. Vegetable peroxidase and bacterial enzymes, including an ''Escherichia coli'' peroxidase, may also cause false-positive reactions. Therefore, sediments containing bacteria should be checked closely for the presence of red blood cells. Traditionally, ascorbic acid (vitamin C) has been associated with false-negative reagent strip reactions for blood. Both Multistix and Chemstrip have modified their reagent strips to reduce this interference to very high levels of ascorbic acid, and Chemstrip overlays the reagent pad with an iodate-impregnated mesh that oxidizes the ascorbic acid prior to its reaching the reaction pad. False-negative reactions can result when urine with a high specific gravity contains crenated red blood cells that do not lyse when they come in contact with the reagent pad. Decreased reactivity may also be seen when formalin is used as a preservative or when the hypertension medication captopril or high concentration of nitrite are present. Red blood cells settle to the bottom of the specimen container, and failure to mix the specimen prior to testing causes a falsely decreased reading.

Diseases identified

With the aid of routine examinations early symptoms of the following four groups can be identified: *Diseases of the kidneys and the urinary tract *Carbohydrate metabolism disorders (diabetes mellitus) *Liver diseases and haemolytic disorders *Urinary infections

Urinary tract

Screening parameters: Many renal and urinary tract diseases may be

asymptomatic In medicine, any disease is classified asymptomatic if a patient tests as carrier for a disease or infection but experiences no symptoms. Whenever a medical condition fails to show noticeable symptoms after a diagnosis it might be considered a ...

for a long period of time. Routine urinalysis is recommended as a basic yet fundamental step in identifying

renal The kidneys are two reddish-brown bean-shaped organs found in vertebrates. They are located on the left and right in the retroperitoneal space, and in adult humans are about in length. They receive blood from the paired renal arteries; bloo ...

damage and/or urinary tract disease at an early stage, especially in high-risk populations such as diabetics, the hypertensive,

African Americans African Americans (also referred to as Black Americans and Afro-Americans) are an ethnic group consisting of Americans with partial or total ancestry from sub-Saharan Africa. The term "African American" generally denotes descendants of ens ...

Polynesians Polynesians form an ethnolinguistic group of closely related people who are native to Polynesia (islands in the Polynesian Triangle), an expansive region of Oceania in the Pacific Ocean. They trace their early prehistoric origins to Island Sou ...

, and those with a

family history Genealogy () is the study of families, family history, and the tracing of their lineages. Genealogists use oral interviews, historical records, genetic analysis, and other records to obtain information about a family and to demonstrate kin ...

. Specific kidney and urinary tract diseases that can be identified include:

chronic kidney disease Chronic kidney disease (CKD) is a type of kidney disease in which a gradual loss of kidney function occurs over a period of months to years. Initially generally no symptoms are seen, but later symptoms may include leg swelling, feeling tired, vo ...

, glomerulonephritis, proteinuria and haematuria.

Protein testing

Of the routine chemical tests performed on urine, the most indicative of renal disease is the protein determination. Proteinuria is often associated with early renal disease, making the urinary protein test an important part of any physical examination. Normal urine contains very little protein, usually less than 100–300 mg/L or 100 mg per 24 hours is excreted. This protein consists primarily of low-molecular-weight serum proteins that have been filtered by the glomerulus and proteins produced in the genitourinary tract. Due to its low molecular weight, albumin is the major serum protein found in the plasma, the normal urinary albumin content is low because the majority of albumin presented in the glomerulus is not filtered, and much of the filtered albumin is reabsorbed by the tubules. Other proteins include small amounts of serum and tubular microglobulins. Uromodulin produced by the renal tubular epithelial cells and proteins from prostatic, seminal, and vaginal secretions. Uromodulin is routinely produced in the distal convoluted tube, and forms the matrix of casts. Traditional reagent strip testing for protein uses the principle of the protein error of indicators to produce a visible colorimetric reaction. Contrary to the general belief that indicators produce specific colours in response to particular pH levels, certain indicators change colour in the presence of protein even though the pH of the medium remains constant. This is so because protein accepts hydrogen ions from the indicator. The test is more sensitive to albumin because albumin contains more amino groups to accept the hydrogen ions than other proteins. Depending on the manufacturer, the protein area of the strip contains different chemicals. Multistix contains tetrabromophenol blue and Chemstrip contains 3’,3”,5’,5”-tetrachlorophenol, 3,4,5,6-tetrabromosulfonphthalein. Both contain an acid buffer to maintain the pH at a constant level. At a pH level of 3, both indicators appear yellow in the absence of protein. However, as the protein concentration increases, the colour progresses through various shades of green and finally to blue. Readings are reported in terms of negative, trace, 1+, 2+, 3+ and 4+ or the semi-quantitative values of 30, 100, 300 or 2000 mg/dL corresponding to each colour change. Trace values are considered to be less than 30 mg/dL. Interpretation of trace readings can be difficult.

Indicator-H⁺_(Yellow) + Protein → Indicator_(Blue-green) + Protein-H⁺

The major source of error with reagent strips occurs with highly buffered alkaline urine that overrides the acid buffer system, producing a rise in pH and a colour change unrelated to protein concentration. Likewise, a technical error of allowing the reagent pad to remain in contact with the urine for a prolonged period may remove the buffer. False-positive readings are obtained when the reaction does not take place under acidic conditions. Highly pigmented urine and contamination of the container with quaternary ammonium compounds, detergents and antiseptics also cause false-positive readings. A false-positive trace reading may occur in specimens with a high specific gravity.

Hemoglobin and myoglobin testing

The presence of

blood Blood is a body fluid in the circulatory system of humans and other vertebrates that delivers necessary substances such as nutrients and oxygen to the cells, and transports metabolic waste products away from those same cells. Blood in the cir ...

in the urine is, of all the parameters normally tested, the one that is most closely related with traumatic damage to the kidneys or the genitourinary tract. The most common causes of hematuria are: nephrolithiasis, glomerular disease,

tumour A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...

pyelonephritis Pyelonephritis is inflammation of the kidney, typically due to a bacterial infection. Symptoms most often include fever and flank tenderness. Other symptoms may include nausea, burning with urination, and frequent urination. Complications ...

, exposure to nephrotoxins, and treatment with

anticoagulant Anticoagulants, commonly known as blood thinners, are chemical substances that prevent or reduce coagulation of blood, prolonging the clotting time. Some of them occur naturally in blood-eating animals such as leeches and mosquitoes, where t ...

s. Non-pathological hematuria can be observed after strenuous exercise and during

menstruation Menstruation (also known as a period, among other colloquial terms) is the regular discharge of blood and mucosal tissue from the inner lining of the uterus through the vagina. The menstrual cycle is characterized by the rise and fall of ...

. The normal number of red blood cells in urine should not usually exceed 3 per high power field. A urine test strip showing positive for blood can also indicate hemoglobinuria, which is not detectable using a microscope due to the lysis of red blood cells in the urinary tract (particularly in alkaline or dilute urine), or

intravascular hemolysis Intravascular hemolysis describes hemolysis that happens mainly inside the vasculature. As a result, the contents of the red blood cell are released into the general circulation, leading to hemoglobinemia and increasing the risk of ensuing hyperb ...

. Under normal conditions the formation of

haptoglobin Haptoglobin (abbreviated as Hp) is the protein that in humans is encoded by the ''HP'' gene. In blood plasma, haptoglobin binds with high affinity to ''free'' hemoglobin released from erythrocytes, and thereby inhibits its deleterious oxidative ...

-hemoglobin complexes prevents glomerular filtration, but if the hemolysis is extensive haptoglobin's uptake capacity is exceeded and hemoglobin can appear in urine. Hemoglobinuria can be caused by hemolytic anaemia, blood transfusions, extensive

burn A burn is an injury to skin, or other tissues, caused by heat, cold, electricity, chemicals, friction, or ultraviolet radiation (like sunburn). Most burns are due to heat from hot liquids (called scalding), solids, or fire. Burns occur ma ...

s, the bite of the

recluse spider The recluse spiders (''Loxosceles'' (), also known as brown spiders, fiddle-backs, violin spiders, and reapers, is a genus of spiders that was first described by R. T. Lowe in 1832. They are venomous spiders known for their bite, which sometimes ...

(Loxosceles), infections and strenuous exercise. The urine test strip test for blood is based on hemoglobin's pseudo peroxidase activity in catalysing a reaction between hydrogen peroxide and the chromogen tetramethylbenzidine in order to produce a dark blue oxidation product. the resultant colour can vary between green and dark blue depending on the amount of hemoglobin. * Catalysed by hemoglobin acting as a peroxidase

H₂O₂ + Chromogen → Oxidised chromogen (coloured) + H₂O

The reaction is not only catalysed by blood hemoglobin, other globins with a hem group such as

myoglobin Myoglobin (symbol Mb or MB) is an iron- and oxygen-binding protein found in the cardiac and skeletal muscle tissue of vertebrates in general and in almost all mammals. Myoglobin is distantly related to hemoglobin. Compared to hemoglobin, myoglob ...

can also catalyse the same reaction. The presence of myoglobin in urine gives a positive reaction in the test strip's blood test but the urine appears clear with a red to brown colouration. The presence of myoglobin in place of hemoglobin can be caused by pathologies associated with muscular damage (

rhabdomyolysis Rhabdomyolysis (also called rhabdo) is a condition in which damaged skeletal muscle breaks down rapidly. Symptoms may include muscle pains, weakness, vomiting, and confusion. There may be tea-colored urine or an irregular heartbeat. Some of ...

), such as

trauma Trauma most often refers to: *Major trauma, in physical medicine, severe physical injury caused by an external source *Psychological trauma, a type of damage to the psyche that occurs as a result of a severely distressing event *Traumatic inju ...

, crush syndrome, prolonged coma,

convulsion A convulsion is a medical condition where the body muscles contract and relax rapidly and repeatedly, resulting in uncontrolled shaking. Because epileptic seizures typically include convulsions, the term ''convulsion'' is sometimes used as a ...

s, progressive muscular atrophy,

alcoholism Alcoholism is, broadly, any drinking of alcohol that results in significant mental or physical health problems. Because there is disagreement on the definition of the word ''alcoholism'', it is not a recognized diagnostic entity. Predomi ...

heroin Heroin, also known as diacetylmorphine and diamorphine among other names, is a potent opioid mainly used as a recreational drug for its euphoric effects. Medical grade diamorphine is used as a pure hydrochloride salt. Various white and bro ...

abuse and strenuous physical activity. The haem fraction of these proteins is toxic for the kidney tubules and elevated concentrations can cause acute kidney injury. It is possible to use an ammonia sulphate precipitation test in order to distinguish between hemoglobinuria and myoglobinuria. This consists of adding 2.8gr of ammonia sulphate to 5 mL of centrifuged urine, mixing well and after 5 minutes filtering the sample and centrifuging again. The hemoglobin precipitates out with the ammonia sulphate but not the myoglobin. Analysis of the supernatant for blood with a test strip will give a positive if myoglobin is present and a negative if hemoglobin is present. The test can give false positives if strong oxidant or peroxide residues are present on the laboratory material used for the analysis.

Carbohydrate disorders

Glucose Glucose is a simple sugar with the molecular formula . Glucose is overall the most abundant monosaccharide, a subcategory of carbohydrates. Glucose is mainly made by plants and most algae during photosynthesis from water and carbon dioxide, u ...

- Identified as Glycosuria *

Ketones In organic chemistry, a ketone is a functional group with the structure R–C(=O)–R', where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group –C(=O)– (which contains a carbon-oxygen double b ...

- Identified as Ketonuria (also see

ketoacidosis Ketoacidosis is a metabolic state caused by uncontrolled production of ketone bodies that cause a metabolic acidosis. While ketosis refers to any elevation of blood ketones, ketoacidosis is a specific pathologic condition that results in changes ...

and

ketosis Ketosis is a metabolic state characterized by elevated levels of ketone bodies in the blood or urine. Physiological ketosis is a normal response to low glucose availability, such as low-carbohydrate diets or fasting, that provides an additional ...

) Around 30–40% of type I diabetics and around 20% of type II diabetics suffer in time from a nephropathy, and early recognition of diabetes is therefore of major significance for the further state of health of these patients. Specific carbohydrate metabolism disorders able to be identified include

Diabetes Mellitus Diabetes, also known as diabetes mellitus, is a group of metabolic disorders characterized by a high blood sugar level ( hyperglycemia) over a prolonged period of time. Symptoms often include frequent urination, increased thirst and increased ...

, Glucosuria and Ketonuria.

Glucose test

Under normal conditions nearly all the

removed in the glomerulus is reabsorbed in the proximal convoluted tubule. If the blood glucose level increases, as happens in diabetes mellitus, the capacity of the convoluted tubule to reabsorb glucose is exceeded (an effect known as ''renal reabsorption threshold''). For glucose this threshold is between 160–180 mg/dL. Glucose concentrations vary in an individual, and a healthy person can present with transitory glucosuria after a meal high in sugars; therefore the most representative results come from samples obtained at least two hours after food is eaten. The detection of glucose by test strips is based on the enzymatic reaction of glucose oxidase. This enzyme catalyses the oxidation of glucose by atmospheric oxygen to form

gluconic acid Gluconic acid is an organic compound with molecular formula C6H12O7 and condensed structural formula HOCH2(CHOH)4COOH. It is one of the 16 stereoisomers of 2,3,4,5,6-pentahydroxyhexanoic acid. In aqueous solution at neutral pH, gluconic acid ...

and

hydrogen peroxide Hydrogen peroxide is a chemical compound with the formula . In its pure form, it is a very pale blue liquid that is slightly more viscous than water. It is used as an oxidizer, bleaching agent, and antiseptic, usually as a dilute solution (3 ...

. A second linked reaction, mediated by a peroxidase, catalyses the reaction between the peroxide and a chromogen (a substance that acquires colour after a chemical reaction) to form a coloured compound that indicates the glucose concentration. :* 1) Catalysed by glucose oxidase

Glucose + O₂ → D-glucono-δ-lactone + H₂O₂

:* 2) Catalysed by peroxidase

H₂O₂ + Chromogen → Oxidised chromogen (coloured) + H₂O

The reaction is specific for glucose, as occurs in all enzymatic reactions, but it can provide some false positive results due to the presence of traces of strong oxidising agents or peroxide from disinfectants used on laboratory instruments.

Ketone test

The term ''

s'' or ''

ketone bodies Ketone bodies are water-soluble molecules that contain the ketone groups produced from fatty acids by the liver ( ketogenesis). Ketone bodies are readily transported into tissues outside the liver, where they are converted into acetyl-CoA (acet ...

'' in reality refers to three intermediate products in the metabolism of

fatty acid In chemistry, particularly in biochemistry, a fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated or unsaturated. Most naturally occurring fatty acids have an unbranched chain of an even number of carbon atoms, f ...

acetoacetic acid Acetoacetic acid (also acetoacetate and diacetic acid) is the organic compound with the formula CHCOCHCOOH. It is the simplest beta-keto acid, and like other members of this class, it is unstable. The methyl and ethyl esters, which are quite sta ...

and

beta-hydroxybutyric acid β-Hydroxybutyric acid, also known as 3-hydroxybutyric acid or BHB, is an organic compound and a beta hydroxy acid with the chemical formula CH3CH(OH)CH2CO2H; its conjugate base is β-hydroxybutyrate, also known as 3-hydroxybutyrate. β-Hydroxyb ...

. Elevated concentrations of ketones are not generally found in urine, as all these substances are completely metabolized, producing energy, carbon dioxide and water. However, the disruption of carbohydrate metabolism can lead to metabolic imbalances and the appearance of ketones as a by-product of the metabolism of an organism's fat reserves. An increase in fat metabolism can be the result of

starvation Starvation is a severe deficiency in caloric energy intake, below the level needed to maintain an organism's life. It is the most extreme form of malnutrition. In humans, prolonged starvation can cause permanent organ damage and eventually, de ...

malabsorption Malabsorption is a state arising from abnormality in absorption of food nutrients across the gastrointestinal (GI) tract. Impairment can be of single or multiple nutrients depending on the abnormality. This may lead to malnutrition and a variety ...

, the inability to metabolize carbohydrates (as occurs, for example, in diabetes) or due to losses from frequent vomiting. The control of urinary ketone is particularly useful in managing and monitoring

diabetes mellitus type 1 Type 1 diabetes (T1D), formerly known as juvenile diabetes, is an autoimmune disease that originates when cells that make insulin (beta cells) are destroyed by the immune system. Insulin is a hormone required for the cells to use blood sugar for ...

. Ketonuria indicates an insulin deficiency that indicates the need to regulate its dosage. An increase in the blood concentration of ketone produces a water-electrolyte imbalance,

dehydration In physiology, dehydration is a lack of total body water, with an accompanying disruption of metabolic processes. It occurs when free water loss exceeds free water intake, usually due to exercise, disease, or high environmental temperature. Mil ...

and if not corrected,

acidosis Acidosis is a process causing increased acidity in the blood and other body tissues (i.e., an increase in hydrogen ion concentration). If not further qualified, it usually refers to acidity of the blood plasma. The term ''acidemia'' describe ...

and in the end

diabetic coma Diabetic coma is a life-threatening but reversible form of coma found in people with diabetes mellitus. Three different types of diabetic coma are identified: #Severe low blood sugar in a diabetic person # Diabetic ketoacidosis (usually type 1 ...

. The three ketone compounds appear in different proportions in the urine, although these proportions are relatively constant in different samples as both the acetone and the beta-hydroxybutyric acid are produced from the acetoacetic acid. The proportions are 78% beta-hydroxybutyric acid, 20% acetoacetic acid and 2% acetone. The test used in the urine test strips is based on the reaction of sodium nitroprusside (nitroferricyanide). In this reaction the acetoacetic acid in an alkali medium reacts with the sodium nitroprusside producing a magenta coloured complex: *

Na₂ e(CN)₅NO+ CH₃COCH₂COOH + 2Na(OH) → Na₄ e(CN)₅-N=CHCOCH₂COOHsub>(magenta) + H₂O

Sodium nitroprusside + Acetoacetic acid + Alkali medium → Pink-magenta complex + Water

The test does not measure beta-hydroxybutyric acid and it is only weakly sensitive to acetone when

glycine Glycine (symbol Gly or G; ) is an amino acid that has a single hydrogen atom as its side chain. It is the simplest stable amino acid ( carbamic acid is unstable), with the chemical formula NH2‐ CH2‐ COOH. Glycine is one of the proteinog ...

is added to the reaction. However, as these compounds are derived from the acetoacetic acid their existence can be assumed and a separate test is not therefore necessary. Those medicines that contain sulfhydryl groups, such as mercaptoethane sulphonate Na ( Mesna) and

captopril Captopril, sold under the brand name Capoten among others, is an angiotensin-converting enzyme (ACE) inhibitor used for the treatment of hypertension and some types of congestive heart failure. Captopril was the first oral ACE inhibitor found ...

and

L-DOPA -DOPA, also known as levodopa and -3,4-dihydroxyphenylalanine, is an amino acid that is made and used as part of the normal biology of some plants and animals, including humans. Humans, as well as a portion of the other animals that utilize -DOPA ...

can give atypical colouring. A false negative can occur in samples that have not been adequately stored due to volatilization and bacterial degradation.

Liver and blood disorders

In many liver diseases the patients often show signs of pathology only at a late stage. Early diagnosis allows appropriate therapeutic measures to be instituted in good time, avoiding consequential damage and further infections. Specific liver diseases and haemolytic disorders able to be identified include liver disease, (accompanied by

jaundice Jaundice, also known as icterus, is a yellowish or greenish pigmentation of the skin and sclera due to high bilirubin levels. Jaundice in adults is typically a sign indicating the presence of underlying diseases involving abnormal heme meta ...

cirrhosis Cirrhosis, also known as liver cirrhosis or hepatic cirrhosis, and end-stage liver disease, is the impaired liver function caused by the formation of scar tissue known as fibrosis due to damage caused by liver disease. Damage causes tissue rep ...

, urobilinogenuria and bilirubinuria.

Bilirubin test

Bilirubin is a highly pigmented compound that is a by-product of haemoglobin degradation. The haemoglobin that is released after the mononuclear phagocyte system (located in the

liver The liver is a major organ only found in vertebrates which performs many essential biological functions such as detoxification of the organism, and the synthesis of proteins and biochemicals necessary for digestion and growth. In humans, it i ...

and

spleen The spleen is an organ found in almost all vertebrates. Similar in structure to a large lymph node, it acts primarily as a blood filter. The word spleen comes .

) withdraws old red blood cells from circulation is degraded into its components;

iron Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in ...

protoporphyrin Protoporphyrin IX is an organic compound, classified as a porphyrin, that plays an important role in living organisms as a precursor to other critical compounds like heme ( hemoglobin) and chlorophyll. It is a deeply colored solid that is not s ...

and

. The system's cells convert the protoporphyrin into

unconjugated bilirubin Bilirubin (BR) (Latin for "red bile") is a red-orange compound that occurs in the normal catabolic pathway that breaks down heme in vertebrates. This catabolism is a necessary process in the body's clearance of waste products that arise from th ...

that passes through the circulatory system bound to protein, particularly albumin. The kidney is unable to filter out this bilirubin as it is bound to protein, however, it is conjugated with

glucuronic acid Glucuronic acid (from Greek γλεῦκος "''wine, must''" and οὖρον "''urine''") is a uronic acid that was first isolated from urine (hence the name). It is found in many gums such as gum arabic (c. 18%), xanthan, and kombucha tea ...

in the liver to form water-soluble conjugated bilirubin. This conjugated bilirubin does not normally appear in the urine as it is excreted directly from the intestine in

bile Bile (from Latin ''bilis''), or gall, is a dark-green-to-yellowish-brown fluid produced by the liver of most vertebrates that aids the digestion of lipids in the small intestine. In humans, bile is produced continuously by the liver (liver bi ...

. Intestinal bacteria reduce the bilirubin to

, which is later oxidised and either excreted with the faeces as stercobilin or in the urine as urobilin. Conjugated bilirubin appears in urine when the normal degradation cycle is altered due to the obstruction of the biliary ducts or when the kidney's functional integrity is damaged. This allows the escape of conjugated bilirubin into the circulation as occurs in

hepatitis Hepatitis is inflammation of the liver tissue. Some people or animals with hepatitis have no symptoms, whereas others develop yellow discoloration of the skin and whites of the eyes ( jaundice), poor appetite, vomiting, tiredness, abdominal ...

and

hepatic cirrhosis Cirrhosis, also known as liver cirrhosis or hepatic cirrhosis, and end-stage liver disease, is the impaired liver function caused by the formation of scar tissue known as fibrosis due to damage caused by liver disease. Damage causes tissue repai ...

). The detection of urinary bilirubin is an early indication of liver disease and its presence or absence can be used to determine the causes of clinical

. The jaundice produced by the accelerated destruction of red blood cells does not produce bilirubinuria, as the high serum bilirubin is found in the unconjugated form and the kidneys are unable to excrete it. The test strips use a

diazotization Diazonium compounds or diazonium salts are a group of organic compounds sharing a common functional group where R can be any organic group, such as an alkyl or an aryl, and X is an inorganic or organic anion, such as a halide. General propert ...

reaction in order to detect bilirubin. The bilirubin combines with a diazonium salt (2,4-dichloroaniline or 2,6-dichlorobenzene-diazonium-tetrafluoroborate) in an acid medium to produce an

azo dye Azo dyes are organic compounds bearing the functional group R−N=N−R′, in which R and R′ are usually aryl and substituted aryl groups. They are a commercially important family of azo compounds, i.e. compounds containing the C-N ...

with colouration that varies from pink to violet: :*In acid medium

Bilirubin glucuronide + Diazonium salt→ Azo dye (violet)

False positive reactions can be due to unusual pigments in the urine (for example, yellowy orange phenazopyridine metabolites, indican and the metabolites of the medicine Lodine ( Etodolac)). False negatives can also be given by poorly stored samples as the bilirubin is photosensitive and undergoes photo oxidation to

biliverdin Biliverdin ( latin for green bile) is a green tetrapyrrolic bile pigment, and is a product of heme catabolism.Boron W, Boulpaep E. Medical Physiology: a cellular and molecular approach, 2005. 984-986. Elsevier Saunders, United States. It is the ...

when it is exposed to light, or hydrolysis of the glucuronide can occur producing free bilirubin which is less reactive.

Urobilinogen test

Intestinal bacteria convert the conjugated bilirubin that is excreted by the bile duct into the intestine into urobilinogen and stercobilinogen. Part of the urobilinogen is reabsorbed in the intestine then circulated in the blood to the liver where it is excreted. A small part of this recirculated urobilinogen is filtered out by the kidneys and appears in urine (less than 1 mg/dL urine). The stercobilinogen can not be reabsorbed and remains in the intestine. Any deterioration in liver function reduces its ability to process the recirculated urobilinogen. The excess that remains in the blood is filtered out by the kidneys and appears in urine. When hemolytic disorders occur the amount of unconjugated bilirubin that is present in the blood increases causing an increase in hepatic excretion of conjugated bilirubin, resulting in increased amounts of urobilinogen that in turn causes an increase in reabsorption, recirculation and renal excretion. The reactions that take place in the test strip vary according to the manufacturer, but in reality there are two reactions that are most frequently used. Some manufacturers use Ehrlich's reaction (1), in which urobilinogen reacts with p-dimethylaminobenzaldehyde (

Ehrlich's reagent Ehrlich's reagent or Ehrlich reagent is a reagent containing ''p''-dimethylaminobenzaldehyde (DMAB) and thus can act as an indicator to presumptively identify indoles and urobilinogen. Several Ehrlich tests use the reagent in a medical test; so ...

) in order to produce colours that vary from light to dark pink. Other manufacturers use a diazo coupling reaction (2) that uses 4-methoxybenzene-diazonium-tetrafluoroborate to produce colours that vary from white to pink. The latter reaction is more specific. :* (1) Reaction on Multistix (in acid medium)

Urobilinogen + p-dimethylaminobenzaldehide → Red dye

:* (2) Reaction on Chemstrip (in acid medium)

Urobilinogen + 4-methoxibenzene-diazonium-tetrafluoroborate → Red azo dye

A number of substances interfere with the Ehrlich reaction on the Multistix strip: porphobilinogen, indican, p-amino salicylic acid, sulphonamide, methyldopa, procaine and chlorpromazine. The test should be carried out at room temperature as the reaction's sensitivity increases with temperature. Poorly stored samples can yield false negative results as the urobilinogen suffers photo oxidation to urobilin that does not react. The formaldehyde used as a preservative produces false negatives in both reactions.

Urinary infections

Urinary infections can be identified including bacteriuria and pyuria.

Nitrites test

The test for nitrites is a rapid screening method for possible asymptomatic infections caused by nitrate-reducing bacteria. Some of the gram negative bacteria species that most commonly cause

urinary tract infection A urinary tract infection (UTI) is an infection that affects part of the urinary tract. When it affects the lower urinary tract it is known as a bladder infection (cystitis) and when it affects the upper urinary tract it is known as a kidne ...

s (

Escherichia coli ''Escherichia coli'' (),Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. also known as ''E. coli'' (), is a Gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus '' Esc ...

Enterobacter ''Enterobacter'' is a genus of common Gram-negative, facultatively anaerobic, rod-shaped, non-spore-forming bacteria of the family Enterobacteriaceae. It is the type genus of the order Enterobacterales. Several strains of these bacteria are ...

Klebsiella ''Klebsiella'' is a genus of Gram-negative, oxidase-negative, rod-shaped bacteria with a prominent polysaccharide-based capsule. ''Klebsiella'' species are found everywhere in nature. This is thought to be due to distinct sublineages devel ...

Citrobacter ''Citrobacter'' is a genus of Gram-negative coliform bacteria in the family Enterobacteriaceae. The species ''C. amalonaticus'', ''C. koseri'', and ''C. freundii'' can use citrate as a sole carbon source. ''Citrobacter'' species are different ...

and

Proteus In Greek mythology, Proteus (; Ancient Greek: Πρωτεύς, ''Prōteus'') is an early prophetic sea-god or god of rivers and oceanic bodies of water, one of several deities whom Homer calls the "Old Man of the Sea" ''(hálios gérôn)''. ...

) have enzymes that reduce the nitrate present in urine to nitrite. The test is a rapid screen for possible infections by enteric bacteria, but it does not replace the

tests nor microscopic examination as diagnostic tools, nor subsequent monitoring as many other microorganisms that do not reduce nitrate (

gram positive In bacteriology, gram-positive bacteria are bacteria that give a positive result in the Gram stain test, which is traditionally used to quickly classify bacteria into two broad categories according to their type of cell wall. Gram-positive bact ...

bacteria and yeasts) can also cause urinary infections. The reactive strips detect nitrite by using the Griess reaction in which the nitrite reacts in an acid medium with an

aromatic In chemistry, aromaticity is a chemical property of cyclic ( ring-shaped), ''typically'' planar (flat) molecular structures with pi bonds in resonance (those containing delocalized electrons) that gives increased stability compared to satur ...

amine In chemistry, amines (, ) are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are formally derivatives of ammonia (), wherein one or more hydrogen atoms have been replaced by a substituent ...

(para-arsanilic acid or sulphanilamide) in order to form a diazonium salt that in turn reacts with tetrahydrobenzoquinoline to produce a pink azo dye. :*1) In an acid medium

Para-arsanilic acid or sulphanilamide + → Diazonium salt

:*2) In an acid medium

Diazonium salt + tetrahydrobenzoquinoline → Pink azo dye

The nitrite test is not particularly reliable and negative results in the presence of clinical symptoms are not uncommon, meaning that the test should not be taken as conclusive. Negative results can be obtained in the presence of non nitrate-reducing microorganisms. Nitrite-reducing bacteria need to remain in contact with nitrate for long enough to produce detectable amounts (first urine produced in the morning or at least with a urine retention of 4 hours). Large numbers of bacteria can react to reduce nitrite to nitrogen, which will give a false negative result. The use of antibiotics will inhibit bacterial metabolism causing negative results even though bacteria are present. In addition some substances such as ascorbic acid will compete with the Greiss reaction giving unrepresentatively low readings.

Leukocytes test

It is normal to find up to 3 (occasionally 5) leukocytes per high power field (40X) in a urine sample, with women having slightly higher results owing to vaginal contamination. Higher numbers indicate urinary infection. The urine test strip test for white blood cells detects leukocyte esterase, which is present in azurophilic granules of

monocytes Monocytes are a type of leukocyte or white blood cell. They are the largest type of leukocyte in blood and can differentiate into macrophages and conventional dendritic cells. As a part of the vertebrate innate immune system monocytes also inf ...

and

granulocyte Granulocytes are cells in the innate immune system characterized by the presence of specific granules in their cytoplasm. Such granules distinguish them from the various agranulocytes. All myeloblastic granulocytes are polymorphonuclear. They ha ...

s ( neutrophilic,

eosinophilic Eosinophilic (Greek suffix -phil-, meaning ''loves eosin'') is the staining of tissues, cells, or organelles after they have been washed with eosin, a dye. Eosin is an acidic dye for staining cell cytoplasm, collagen, and muscle fibers. ''E ...

and basophilic). Bacteria, lymphocytes and epithelial cells from the genitourinary tract do not contain esterases. Neutrophil granulocytes are the leukocytes most commonly associated with urinary infections. A positive test for leukocyte esterase normally indicates the presence of bacteria and a positive nitrite test (although it is not always the case). Infections caused by

Trichomonas ''Trichomonas'' is a genus of anaerobic excavate parasites of vertebrates. It was first discovered by Alfred François Donné in 1836 when he found these parasites in the pus of a patient suffering from vaginitis, an inflammation of the vagina ...

Chlamydia Chlamydia, or more specifically a chlamydia infection, is a sexually transmitted infection caused by the bacterium '' Chlamydia trachomatis''. Most people who are infected have no symptoms. When symptoms do appear they may occur only several we ...

and yeasts produce leukocyturia without bacteriuria. The inflammation of the renal tissues (

interstitial nephritis Interstitial nephritis, also known as tubulointerstitial nephritis, is inflammation of the area of the kidney known as the renal interstitium, which consists of a collection of cells, extracellular matrix, and fluid surrounding the renal tubul ...

) can produce leukocyturia, in particular toxic interstitial nephritis with predominant eosinophils. The test for leukocyte esterase is purely indicative and should not be solely relied on for diagnosis, as it does not replace microscopic or urine culture examinations. The urine test strip reaction is based on the action of leukocyte esterase in catalysing the hydrolysis of an ester of indolecarboxylic acid. The indoxyl that is liberated combines with a diazonium salt in order to produce a violet coloured azole dye. :*1) Reaction catalysed by leukocyte esterase

Indolecarboxylic acid ester → Indoxyl + Acid

:*2) In acid medium

Indoxyl + Diazonium salt → Violet azole dye

The esterase reaction needs about 2 minutes to take place. The presence of strong oxidising agents or formaldehyde can cause false positives. False negative results are associated with elevated concentrations of protein (greater than 500 mg/dL), glucose (greater than 3 g/dL),

oxalic acid Oxalic acid is an organic acid with the systematic name ethanedioic acid and formula . It is the simplest dicarboxylic acid. It is a white crystalline solid that forms a colorless solution in water. Its name comes from the fact that early invest ...

and

ascorbic acid Vitamin C (also known as ascorbic acid and ascorbate) is a water-soluble vitamin found in citrus and other fruits and vegetables, also sold as a dietary supplement and as a topical 'serum' ingredient to treat melasma (dark pigment spots) ...

. Urine with a high specific gravity can also cause leukocyte crenation, which can impede the liberation of the esterases.

Detection limit

The detection limit of a test is the concentration at which the test starts to turn from negative to positive. Although the detection limit may vary between urine samples, the detection limit is defined as the concentration of the analyte that results in a positive reaction in 90% of the examined urines.

Medical uses

Urine test strips can be used in many areas of the healthcare chain including screening for routine examinations, treatment monitoring, self-monitoring by patients and/or general preventive medicine.

Screening

Urine test strips are used for

screening Screening may refer to: * Screening cultures, a type a medical test that is done to find an infection * Screening (economics), a strategy of combating adverse selection (includes sorting resumes to select employees) * Screening (environmental), ...

both in hospitals and in general practice. The aim of screening is early identification of likely patients by examination of large groups of the population. The importance of screening for diabetes and kidney disease amongst high-risk populations is becoming very high.

Treatment monitoring

Treatment monitoring with the aid of urine test strips allows a health professional to check on the results of the prescribed therapy, and if necessary to introduce any changes into the course of therapy.

Self-monitoring

Self-monitoring with urine test strips under the guidance of a health professional is an effective method for monitoring the disease state. This applies particularly to

diabetic Diabetes, also known as diabetes mellitus, is a group of metabolic disorders characterized by a high blood sugar level (hyperglycemia) over a prolonged period of time. Symptoms often include frequent urination, increased thirst and increased ap ...

s, where the idea of self-monitoring of the metabolic status (determinations of glucose and ketones) is self-evident.

Veterinary

In veterinary medicine, especially in cats and dogs, the test strip can be used for urinalysis.

History

In many cultures urine was once regarded as a mystical fluid, and in some cultures it is still regarded as such to this day. Its uses have included wound healing, stimulation of the body's defences, and examinations for diagnosing the presence of diseases. It was only towards the end of the 18th century that doctors interested in chemistry turned their attention to the scientific basis of

and to its use in practical medicine. *1797 - Carl Friedrich Gärtner (1772–1850) expressed a wish for an easy way of testing urine for disease at the patient's bedside. *1797 -

William Cumberland Cruikshank William Cumberland Cruikshank (1745 in Edinburgh – 27 June 1800) was a British physician and anatomist. He was the author of ''The Anatomy of the Absorbing Vessels of the Human Body'', which was first published in 1786.Pilcher, Lewis Stephe ...

(1745–1800) described for the first time the property of coagulation on heating, exhibited by many urines. *1827 - English physician Richard Bright describes the clinical symptom of nephritis in “Reports of Medical Cases.” *1840 - The arrival of chemical urine diagnostics aimed at the detection of pathological urine constituents *1850 - Parisian chemist Jules Maumené (1818–1898) develops the first “test strips” when he impregnated a strip of merino wool with “tin protochloride” (stannous chloride). On application of a drop of urine and heating over a candle the strip immediately turned black if the urine contained sugar. *1883 - English physiologist George Oliver (1841–1915) markets his “Urinary Test Papers” *approx. 1900 -

Reagent In chemistry, a reagent ( ) or analytical reagent is a substance or compound added to a system to cause a chemical reaction, or test if one occurs. The terms ''reactant'' and ''reagent'' are often used interchangeably, but reactant specifies a ...

papers become commercially obtainable from the chemical company of Helfenberg AG. *1904 - A test for the presence of blood by a wet-chemical method using benzidine became known. *approx. 1920 - Viennese chemist

Fritz Feigl Fritz Feigl (15 May 1891 – 23 January 1971) was a Jewish Austrian-born chemist. He taught at the University of Brazil. Biography Feigl was born and studied in Vienna, but owing to his military service in the First World War he had to interr ...

(1891–1971) publishes his technique of “ spot analysis". *1930s - Urine diagnostics makes major progress as reliability improves and test performance becomes progressively easier. *1950s - Urine test strips in the sense used today were first made on industrial scale and offered commercially. *1964 - The company

Boehringer Mannheim F. Hoffmann-La Roche AG, commonly known as Roche, is a Swiss multinational healthcare company that operates worldwide under two divisions: Pharmaceuticals and Diagnostics. Its holding company, Roche Holding AG, has shares listed on the SIX ...

, today

Roche F. Hoffmann-La Roche AG, commonly known as Roche, is a Swiss multinational healthcare company that operates worldwide under two divisions: Pharmaceuticals and Diagnostics. Its holding company, Roche Holding AG, has shares listed on the SIX ...

, launched its first Combur test strips. Even though the test strips have changed little in appearance since the 1960s, they now contain a number of innovations. New impregnation techniques, more stable colour indicators, and the steady improvement in colour gradation have all contributed to the fact that the use of urine test strips has now become established in clinical and general practice as a reliable diagnostic instrument. The parameter menu offered has steadily grown longer in the intervening decades.

Ascorbic acid interference

Ascorbic acid (vitamin C) is known to interfere with the oxidation reaction of the blood and glucose pad on common urine test strips. Some urine test strips are protected against the interference with iodate, which eliminates ascorbic acid by oxidation. Some test strips include a test for urinary ascorbate.

Urinary sediment

During routine screening, if a positive test for leukocytes, blood, protein, nitrite, and a pH greater than 7 is identified, the urine

sediment Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sand ...

be microscopically analysed to further pinpoint a diagnosis.

Automated analysers

Automatic analysis of urine test strips using automated urine test strip analysers is a well-established practice in modern-day urinalysis. They can measure

calcium Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar ...

, blood, glucose, bilirubin, urobilinogen, ketones, leukocytes, creatinine, microalbumin, pH, ascorbic acid and protein.