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Uric acid is an organic compound of carbon, nitrogen, oxygen and hydrogen and the structure shown right:

Uric acid is the final oxidation product of purine metabolism in the human body and is found in small amounts in urine. Purine precursors include xanthine and hypoxanthine, which are converted to uric acid by xanthine oxidase.

Uric acid is the end product of nitrogen metabolism in birds and reptiles, whereas in humans and many other animals the main product of nitrogen detoxification is urea. In animals that produce uric acid in high quantities, it is excreted in feces. Humans produce only small quantities of uric acid with excess production leading to a type of arthritis known as gout.

In human blood, uric acid concentrations between 3.6 and 8.3 mg/dL are considered normal by the American Medical Association, although significantly lower levels are common in vegetarians.

Unlike urea and ammonia, uric acid can be excreted as a dry solid. While this compound is more energetic than those other wastes, it means that water loss due to its elimination can be reduced to a minimum. It is therefore commonly found in the excretions of animals that live in very dry environments. The high nitrogen content of uric acid makes guano a useful agricultural fertilizer.

Uric acid is a bicyclic acid derived from purine with a chemical formula of C 5 H 4 N 4 O 3.

Uric acid is a bicyclic acid derived from purine with a chemical formula of C 5 H 4 N 4 O 3.

Uric acid electrode:

Principle

The Universal Sensors Uric Acid Electrode measures dissolved uric acid. Uricase (EC 1.7.3.3) is chemically immobilized in a membrane which is in contact on one side with the sample solution and on the other with the amperometric electrode. Uric acid diffuses into the enzyme layer where it is oxidized by the enzyme according to the reaction:

uric acid + O2 + 2H2O ------------> H2O2 + CO2 + allantoin

The decrease in oxygen at the electrode surface is directly proportional to the uric acid concentration in the sample solution. The maximum, initial rate of response obtained at 5 to 12 seconds or the steady state response obtained after one minute can be used to determine uric acid.

The concentration can be obtained from a calibration curve, an equation or directly from the display of the Universal Sensors Amperometric Biosensor Detector.

Specifications

Uric acid crystals that are deposited in joints is the source of symptoms for gout, a painful condition of joints, usually in the big toes. Damage to kidneys can also occur. Gout is being thought to be related to a condition called insulin resistance. Uric acid is a breakdown product of protein metabolism, particularly of a class of proteins called purines, which are found in organ meats, sardines, anchovies, and lentils. It is possible to go through life with elevated uric acid and never experience symptoms of gout. Good drug treatments exist for acute attacks of gouty arthritis and for reduction of serum uric acid between attacks,

but a few simple measures may enable you to minimize or avoid the use of drugs. Eat a somewhat lower carbohydrate diet, avoiding high glycemic index foods. Be careful with the high purine foods mentioned above. Don't take protein supplements. Eliminate coffee and all other sources of caffeine from the diet. Caffeine and related drugs can raise uric acid levels. Always drink plenty of water to keep urine output high. This will help flush uric acid out of the system and prevent deposition of crystals in the urinary tract. Minimize consumption of alcohol.

Elevations of uric acid

occur in renal diseases with renal failure4 and prerenal azotemia (eg, dehydration) as well as gout.2 Other drugs causing increased uric acid concentration include diuretics,2,4 pyrazinamide, ethambutol, nicotinic acid, and aspirin in low doses.