Pentosuria is a condition where the sugar
xylitol
Xylitol is a chemical compound with the formula , or HO(CH2)(CHOH)3(CH2)OH; specifically, one particular stereoisomer with that structural formula. It is a colorless or white crystalline solid that is freely soluble in water. It can be classifi ...
,
a
pentose
In chemistry, a pentose is a monosaccharide (simple sugar) with five carbon atoms. The chemical formula of many pentoses is , and their molecular weight is 150.13 g/mol.[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.
Cellular ...]
in unusually high concentrations. It was characterized as
an inborn error of carbohydrate metabolism in 1908.
It is associated with a deficiency of
L-xylulose reductase, necessary for xylitol metabolism.
L-
Xylulose is a
reducing sugar
A reducing sugar is any sugar that is capable of acting as a reducing agent. In an alkaline solution, a reducing sugar forms some aldehyde or ketone, which allows it to act as a reducing agent, for example in Benedict's reagent. In such a reacti ...
, so it may give false diagnosis of diabetes, as it is found in high concentrations in urine. However glucose metabolism is normal in people with pentosuria, and they are not
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 ...
.
Patients of pentosuria have a low concentration of the sugar d-xyloketose. Using phenyl pentosazone crystals, phloroglucin reaction, and absorption spectrum, pentose can be traced back as the reducing substance in urine, with those that have pentosuria.
Research has shown that pentosuria appears in 3 forms. The most widely studied is essential pentosuria, where a couple of grams of L-xylusol are released into a person's system daily.
, contained in red blood cells, is composed of both a major and minor
isozyme In biochemistry, isozymes (also known as isoenzymes or more generally as multiple forms of enzymes) are enzymes that differ in amino acid sequence but catalyze the same chemical reaction. Isozymes usually have different kinetic parameters (e.g. dif ...
.
For those diagnosed with essential pentosuria, the major isozyme appears to be the same as the minor one.
Alimentary pentosuria can be acquired through fruits high in pentose.
Finally, drug-induced pentosuria can be developed by those exposed to morphine, fevers, allergies, and some hormones.
Those diagnosed with Pentosuria are predominantly of Jewish root.
However, it is a harmless defect, and no cure is needed.
References
External links
Urine
{{endocrine-disease-stub
Inborn errors of carbohydrate metabolism