Uric Acid, 24-Hour Urine

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Category:

Turnaround Time: Within 1 day
CPT Code: 84560
Test Type: 10 mL aliquot, Urine (24-hour)
Stability Time:

Temperature

Period

Room temperature

14 days

Refrigerated

14 days

Frozen

14 days

Freeze/thaw cycles

Stable x3
Reference Range:

Age

Male (mg/24 hr)

Female (mg/24 hr)

0 to 5 y

Not established

Not established

6 to 12 y

87–600

87–600

13 to 17 y

140–804

140–804

18 to 60 y

197–1079

174–902

61 to 70 y

182–937

142–713

>70 y

136–771

89–569

Overview:

Look for hyperuricosuria in patients with renal calculus formation. Identification of overexcretors re: risks of stone formation, identification of genetic defects, influence of overexcretion on therapy of gout. Uric acid nephrolithiasis occurs in primary gout or in secondary hyperuricemia (eg, malignant diseases). Uric acid nephrolithiasis may complicate ulcerative colitis, Crohn's disease, and surgical jejunoileal bypass. Most subjects with uric acid stones do not have gout.1 Evaluate uric acid metabolism in gout.

Even mild renal failure decreases uric acid excretion. Uric acid excretion is decreased with hypertension.

A young patient with acute gouty arthritis, uric acid stones, and any patient who excretes >1000 mg uric acid/24 hours, should be evaluated for HPRT deficiency.2 The uric acid:creatinine ratio has been used as a test for Lesch-Nyhan syndrome (HPRTase deficiency). Normal control patients 0.21−0.59; partial enzyme deficient group 0.62−2.00; complete enzyme deficiency 1.98−5.35.3

The ratio of uric acid:creatinine in morning samples of urine has been used as a test for detection of the Lesch-Nyhan syndrome, which is associated with virtually complete absence of activity of the enzyme hypoxanthine-guanine phosphoribosyltransferase. This ratio has also been applied to 24-hour urine samples from adult patients with gout for detection of partial deficiency of the same enzyme. The uric acid:creatinine ratio in the urine of normal control patients is reported to range from 0.21−0.59. Patients with gout exhibit ratios of 0.15−0.73, whereas those patients with hyperuricemia associated with another disorder such as leukemia or glycogen-storage disease have ratios of 0.25−1.77. The ratio is 0.27−0.58 for patients with nongouty arthritis. Patients with complete hypoxanthine-guanine phosphoribosyltransferase deficiency are reported to have urinary uric acid:creatinine ratios of 1.98−5.35, as compared to 0.62−2.00 for patients with gout accompanied by partial enzyme deficiency.

The ratio of uric acid:creatinine concentration on a random urine specimen has also been shown to be >1.0 in patients with acute renal failure secondary to acute uric acid nephropathy, but <1.0 in patients with acute renal failure resulting from other causes.

1. Pak CY. Renal calculi. In: Wyngaarden JB, Smith LH Jr, eds. Cecil Textbook of Medicine. 18th ed, vol 1. Philadelphia, Pa: WB Saunders Co;1988:638-644.

2. Wilson JM, Young AB, Kelley WN. Hypoxanthine-guanine phosphoribosyltransferase deficiency. The molecular basis of the clinical syndromes. N Engl J Med. 1983 Oct 13; 309(15):900-910 (review). PubMed 6136913

3. Pesce AJ, Kaplan LA. Methods in Clinical Chemistry. St Louis, Mo: Mosby-Year Book Inc;1987: 32.

Collection Details:

Patient Preparation:

Standard diet 24 hours prior to collection.

Collection Instructions:

State urine volume on the request form.

Plastic urine container, no preservative.

Mix well.

Maintain specimen at room temperature or refrigerate.