Citric Acid (Citrate), 24-Hour Urine

Also known as: Citrate Excretion, Urine, Citrate, Urine

Clinical Use

Use

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.

Special Instructions

Not provided.

Limitations

This test was developed and its performance characteristics determined by Labcorp. It has not been cleared or approved by the Food and Drug Administration.

Test Details

Methodology

Other

Biomarkers

Citric Acid (Citrate)

Analyte

Citric Acid, Urine

Concentration / Level • Quantitative (Continuous) (e.g., copies/mL, % expression)

Citric Acid, U, 24hr

Concentration / Level • Quantitative (Continuous) (e.g., copies/mL, % expression)

LOINC Codes

Result Codes

21203-5 - Citrate 24h Ur-mCnc
6687-8 - Citrate 24h Ur-mRate

Result Turnaround Time

2-7 days

Specimen

Urine

Volume

2 mL aliquot

Minimum Volume

1 mL aliquot

Container

Plastic Labcorp 24-hour urine container with 30 mL 6N HCl preservative (Labcorp No. 21584)

Collection Instructions

Collect 24-hour urine with 30 mL 6N HCl. Caution: Strong acid. Mix well. Instruct the patient to void at 8 a.m. and discard the specimen. Then collect all urine including the final specimen voided at the end of the 24-hour collection period (i.e., 8 a.m. 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 aliquot to the laboratory. Alternatively, the sample may be frozen without added acid.

Storage Instructions

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

Causes for Rejection

Citrate: Boric Acid used as a preservative (Boric acid ≥1250 mg/dL may cause citrate results to be reduced by approximately 30%); multivitamin ≥397.5 mg/dL (estimated as 1 pill per day) may cause citrate results to be unmeasurable. Results of interference testing may not be representative of in-vivo characteristics of multivitamin consumption.