Uric Acid, 24 Hour, Urine
Assessment and management of patients with kidney stones, particularly uric acid stones
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Uric acid is the end-product of purine metabolism. It is freely filtered by the glomeruli and most is reabsorbed by the tubules. There is also active tubular secretion.
Increased levels of uric acid in the urine usually accompany increased plasma uric acid levels unless there is a decreased excretion of uric acid by the kidneys. Urine uric acid levels reflect the amount of dietary purines and also endogenous nucleic acid breakdown.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
Diet-dependent: <750 mg/specimen
The reference value is for a 24-hour collection. Specimens collected for other than a 24-hour time period are reported in unit of mg/dL for which reference values are not established.
Urinary uric acid excretion is elevated in a significant proportion of patients with uric acid stones.
Uric acid excretion can be either decreased or increased in response to a variety of pharmacologic agents.
Urine uric acid levels are elevated in states of uric acid overproduction such as in leukemia and polycythemia and after intake of food rich in nucleoproteins.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
High levels of bilirubin and ascorbic acid may interfere with measurement.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
Newman DJ, Price CP: Renal function and nitrogen metabolites. In Textbook of Clinical Chemistry. Edited by NW Tietz. Philadelphia, WB Saunders Company, 1999, pp 1245-1250