Uric acid

Uric Acid

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, anchovies, lentils, mushrooms, spinach, and asparagus are all rich sources of purines. The kidneys excrete uric acid as a waste product. The kidneys excrete two-thirds of the uric acid produced daily; the remaining one-third is excreted in the stool. The exact level of uric acid that is considered pathological is controversial. In recent years, it has been recognized that the normal ranges of uric acid are quite wide. Because of this wide range, and because uric acid levels show day-to-day and seasonal variations in the same person, several uric acids levels may be ordered over a period of time. Urine uric acid levels may also be used to evaluate gout or determine oversecretion of uric acid.

Reference values: Serum Uric Acid

Adult males: 2.0 - 7.5 mg/dl
Adult females: 2.0 - 6.5 mg/dl; in early pregnancy uric acid levels fall by about one-third but rise to non-pregnant levels by term
Children (ages 10-18)
- Males: 3.6 - 5.5 mg/dl; significant rise in males at ages 12-14 coincides with puberty.
- Females: 3.6 - 4 mg/dl
Elderly:
- Males older than 40: 2 - 8.5 mg/dl
- Females older than 40: 2 - 8.0 mg/dl; rise in women related to menopause

The normal range for urinary uric acid is between 250 - 750 mg over a 24-hour period. Uric acid levels tend to vary day to day. It is also important to check the laboratory reference values for each work setting.

An elevated blood uric acid level, also known as hyperuricemia, is seen in:

Gout
Renal disease and renal failure
Alcoholism
Dehydration
Leukemia and lymphoma
Starvation
Metabolic acidosis
Toxemia of pregnancy
Infectious mononucleosis
Hyperlipidemia
Hemolytic anemia
Excessive cell destruction associated with chemotherapy and radiation treatment

An overproduction of uric acid occurs when there is excessive cell breakdown and catabolism of nucleonic acids such as seen in gout, excessive production and destruction of cells, as may occur in leukemia or during cancer therapy, or problems with uric acid excretion due to renal failure.

Decreased serum uric acid levels are usually associated with an increase in plasma volume such as with SIADH.

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A patient receiving intensive cancer therapy with chemotherapy and radiation may have lower than normal uric acid levels.

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