Uric acid

Uric acid is an organic compound of carbon, nitrogen, oxygen and hydrogen with the formula C5H4N4O3. Uric acid is the end product of purine metabolism. Purines are obtained from both dietary sources and from the breakdown of body proteins. Organ meats such as liver, kidneys, and sweetbreads, sardines, lentils, mushrooms, spinach, and asparagus are all rich sources of purines. The kidneys excrete two-thirds of the uric acid produced daily as a waste product; the remaining one-third is excreted in the stool.

High levels of uric acid in the blood is due to increased conversion of purines or decreased excretion of urate by kidney, which can build up in the body (joint of extremities and renal interstitium) causing a painful condition called gout. If gout remains untreated, uric acid crystals can build up in the joints and nearby tissues forming hard deposits called tophi. High levels of uric acid may also cause kidney stones or kidney failure.

Metabolic processes Nucleotidases Nucleoside phosphorylasesPurine Nucleoside Xanthine(AMP, GMP) Xanthine oxidase

Uric acidWhy urate measured? Help diagnose gout. Check if kidney stones may be caused by high uric acid levels in the body. Check to see if medicine that increases or decreases uric acid levels is working. Check its levels in people who are taking chemotherapy or radiation therapy.

ResultsNormal:

Men: 3.4 mg/dL 202 µmol/L

Women: 2.4 mg/dL 143 µmol/L

Children: 2.5 mg/dL 119 µmol/L

High values: High uric acid values may be caused by: Individual differences in the way your body uses or gets rid of uric acid. Diseases, such as:

o Kidney disease or kidney damage.o The increased breakdown of body cells that occurs with some types of cancer (including leukemia, lymphoma, and multiple myeloma), hemolytic anemia, sickle cell anemia, or heart failure.

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o Other disorders like alcohol dependence, preeclampsia, liver cirrhosis, lipid disorders, obesity, psoriasis, hypothyroidism, and hypoparathyroidism. o Starvation, malnutrition, or lead poisoning.o A rare inherited gene disorder called Lesch-Nyhan syndrome.

Medicines, such as some diuretics, vitamin C, aspirin, phenylbutazone.

Low values: Severe liver disease, heavy metal poisoning, Wilson's disease, some cancer. The syndrome of inappropriate antidiuretic hormone (SIADH) Not eating enough protein. Taking too much aspirin.

What Affects the Test? Some medicines may increase the level of uric acid in the blood. These

include diuretics, theophylline, aspirin, and some antituberculosis. The vitamin niacin, high doses of vitamin C, caffeine, and a substance found

in chocolate and tea (theobromine). Excessive use of alcohol, starvation, a high-protein diet, strenuous exercise. Some medicines may decrease the level of uric acid in the blood, like

aspirin, probenecid, and allopurinol.

What to Think AbouT? Having a high uric acid level does not mean that you have gout, ie; you will

not need to take any medicine to decrease your uric acid level. A high level of uric acid in the blood does not always mean that a person

with a painful joint has gout. Testing affected joint fluid for the presence of uric acid crystals is the only sure method to diagnose gout.

If you have kidney disease or have had a problem with kidney stones, your doctor may start treatment even if your uric acid levels are not too high.

Uric acid may also be measured in urine, if your blood uric acid level is high, a 24-hour urine collection may help determine whether your body is producing too much uric acid or your kidneys are not getting rid it.

Uric acid blood levels vary from day to day. The level is usually higher in the morning and lower in the evening.

Blood uric acid levels that increase during pregnancy, even if the levels remain within the normal range, may help diagnose preeclampsia.

MethodsMethod 1: Phosphotungstic acid;Method2: High-performance liquid chromatography; Method 3: Uricase; Oxidation of uric acid to allantoin, hydrogen peroxide, and carbon dioxide; uric acid absorbs in the 290 to 293 nm (at pH 7) but allantoin does not.

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