Acute uric acid nephropathy (AUAN, also acute urate nephropathy) is a rapidly worsening (decreasing)

kidney In humans, the kidneys are two reddish-brown bean-shaped blood-filtering organ (anatomy), organs that are a multilobar, multipapillary form of mammalian kidneys, usually without signs of external lobulation. They are located on the left and rig ...

function (

acute kidney injury Acute kidney injury (AKI), previously called acute renal failure (ARF), is a sudden decrease in renal function, kidney function that develops within seven days, as shown by an increase in serum creatinine or a decrease in urine output, or both. ...

) that is caused by high levels of

uric acid Uric acid is a heterocyclic compound of carbon, nitrogen, oxygen, and hydrogen with the Chemical formula, formula C5H4N4O3. It forms ions and salts known as urates and acid urates, such as ammonium acid urate. Uric acid is a product of the meta ...

in the

urine Urine is a liquid by-product of metabolism in humans and many other animals. In placental mammals, urine flows from the Kidney (vertebrates), kidneys through the ureters to the urinary bladder and exits the urethra through the penile meatus (mal ...

(

hyperuricosuria Hyperuricosuria is a medical term referring to the presence of excessive amounts of uric acid in the urine. For men this is at a rate greater than 800 mg/day, and for women, 750 mg/day. Notable direct causes of hyperuricosuria are disso ...

Causes

Acute uric acid nephropathy is usually seen as part of the acute

tumour lysis syndrome Tumor lysis syndrome (TLS) is a group of metabolic abnormalities that can occur as a complication from the treatment of cancer, where large amounts of tumor cells are killed off ( lysed) from the treatment, releasing their contents into the blood ...

in patients undergoing chemotherapy or radiation therapy for the treatment of malignancies with rapid cell turnover, such as

leukemia Leukemia ( also spelled leukaemia; pronounced ) is a group of blood cancers that usually begin in the bone marrow and produce high numbers of abnormal blood cells. These blood cells are not fully developed and are called ''blasts'' or '' ...

and

lymphoma Lymphoma is a group of blood and lymph tumors that develop from lymphocytes (a type of white blood cell). The name typically refers to just the cancerous versions rather than all such tumours. Signs and symptoms may include enlarged lymph node ...

. It may also occur in these patients before treatment is begun, due to spontaneous tumor cell lysis (high incidence in

Burkitt's lymphoma Burkitt's lymphoma is a cancer of the lymphatic system, particularly B lymphocytes found in the germinal center. It is named after Denis Parsons Burkitt, the Irish surgeon who first described the disease in 1958 while working in equatorial Africa ...

). Acute uric acid nephropathy can also be caused by an acute attack of

gout Gout ( ) is a form of inflammatory arthritis characterized by recurrent attacks of pain in a red, tender, hot, and Joint effusion, swollen joint, caused by the deposition of needle-like crystals of uric acid known as monosodium urate crysta ...

Pathophysiology

Acute uric acid nephropathy is caused by deposition of uric acid crystals within the kidney interstitium and tubules, leading to partial or complete obstruction of collecting ducts, renal pelvis, or ureter. This obstruction is usually bilateral, and patients follow the clinical course of

acute kidney failure Acute may refer to: Language * Acute accent, a diacritic used in many modern written languages * Acute (phonetic), a perceptual classification Science and mathematics * Acute angle ** Acute triangle ** Acute, a leaf shape in the glossary of leaf m ...

Diagnosis

The picture of acute kidney failure is observed: decreased urine production and rapidly rising serum

creatinine Creatinine (; ) is a breakdown product of creatine phosphate from muscle and protein metabolism. It is released at a constant rate by the body (depending on muscle mass). Biological relevance Serum creatinine (a blood measurement) is an impor ...

levels. Acute uric acid nephropathy is differentiated from other forms of acute kidney failure by the finding of a urine uric acid/creatinine ratio > 1 in a random urine sample.

Prevention

Patients at risk for acute uric acid nephropathy can be given

allopurinol Allopurinol is a medication used to decrease hyperuricemia, high blood uric acid levels. It is specifically used to prevent gout, prevent specific types of kidney stones and for the high uric acid levels that can occur with chemotherapy. It i ...

or rasburicase (a recombinant urate oxidase) prior to treatment with cytotoxic drugs.

Treatment

Treatment is focused on preventing deposition of uric acid within the urinary system by increasing urine volume with potent diuretics such as

furosemide Furosemide, sold under the brand name Lasix among others, is a loop diuretic medication used to treat edema due to heart failure, liver scarring, or kidney disease. Furosemide may also be used for the treatment of high blood pressure. It can ...

. Raising the urinary pH to a level higher than 7 (alkalinization) is often difficult to attain, although

sodium bicarbonate Sodium bicarbonate ( IUPAC name: sodium hydrogencarbonate), commonly known as baking soda or bicarbonate of soda (or simply “bicarb” especially in the UK) is a chemical compound with the formula NaHCO3. It is a salt composed of a sodium cat ...

and/or

acetazolamide Acetazolamide, sold under the trade name Diamox among others, is a medication used to treat glaucoma, epilepsy, acute mountain sickness, periodic paralysis, idiopathic intracranial hypertension (raised brain pressure of unclear cause), heart f ...

are sometimes used in an attempt to increase uric acid solubility. Dialysis (preferably

hemodialysis Hemodialysis, American and British English spelling differences#ae and oe, also spelled haemodialysis, or simply ''"'dialysis'"'', is a process of filtering the blood of a person whose kidneys are not working normally. This type of Kidney dialys ...

) is started if the above measures fail.

References

* * * {{ISBN, 978-0-07-140235-4 Kidney diseases