Citric Acid (Citrate), 24-Hour Urine

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Turnaround Time: 2 - 5 days
CPT Code:


Test Type: 10 mL aliquot Urine (24-hour), acidified or frozen
Stability Time:



Room temperature

14 days


14 days


14 days

Freeze/thaw cycles

Stable x3

Reference Range:

320-1240 mg/24 hours


The mean urinary citrate excretion rate in patients with idiopathic calcium urolithiasis has been found to be significantly lower than that of control groups. Hypocitraturia is common in patients with urolithiasis resulting from renal tubular acidosis and in patients with enteric hyperoxaluria. Citrate excretion is low in renal insufficiency.

Collection Details:

Collection Instructions:

Record entire 24-hour total volume on the request form. pH must be 1 to 3 or the sample frozen without the addition of acid.

Plastic LabCorp 24-hour urine container with 30 mL 6N HCl preservative (LabCorp N° 21584).

Collect 24-hour urine with 30 mL 6N HCl. Caution: Strong acid. Mix well. Instruct the patient to void at 8 AM and discard the specimen. Then collect all urine including the final specimen voided at the end of the 24-hour collection period (ie, 8 AM the next morning). Screw the lid on securely. Container must be labeled with patient's full name and date and time collection started and finished. Keep container refrigerated during collection. Preservative is not necessary during collection but should be added to urine collection within 24 hours. Final pH must be 1 to 3. Measure and record on the request form 24-hour total volume and send 25 mL aliquot to the laboratory. Alternatively, the sample may be frozen without added acid.

Refrigerate at 2°C to 8°C after collection.