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Test Directory Citric Acid, 24-Hour Urine without Creatinine

Citric Acid, 24-Hour Urine without Creatinine

Test Summary

This quantitative citric acid test, performed with a 24-hour urine specimen, may help assess the risk of calcium stone formation in the kidneys and inform patient management [1]. In general, 24-hour urine specimens are preferred to random urine specimens when measuring citric acid for diagnostic evaluation and monitoring of calcium nephrolithiasis [2].

Citrate inhibits calcium stone formation by binding and solubilizing calcium, which reduces supersaturation of calcium salts [1-2]. Approximately half of the patients with calcium stones have decreased urinary citrate levels [1]. Citrate is among several substances routinely screened to evaluate the risk of forming kidney stones. Low urinary citrate levels may indicate oral citrate treatment in patients with recurrent calcium nephrolithiasis [1]. Other conditions that can cause hypocitraturia include distal renal tubular acidosis, malabsorption, and urinary tract infection [1].

This test is also available with creatinine (Citric Acid, 24-Hour Urine with Creatinine). Because daily urine excretion of creatinine fluctuates little, creatinine excretion can help determine if 24-hour urine specimens for citric acid have been completely and accurately collected [1].

The urinary citric acid level cannot be used to estimate dietary intake because other factors, such as acid-base balance, may affect citrate excretion [2].

The results of this test should be interpreted in the context of pertinent clinical and family history and physical examination findings.

References
1. Delaney, PM et al. Kidney disease. In: Rifai R, et al. eds. Tietz Textbook of Laboratory Medicine. 7th ed. Elsevier Inc; 2022.
2. Williams JC Jr, et al. Urolithiasis. 2021;49(1):1-16.

Aliases

Specimen Collection

Special Instructions

N/A

Preferred Specimen

10 mL of a 24-hour urine collected in a 24 hour urine container - no preservative

Minimum Volume

1.5 mL

Instructions

Do not include first morning specimen; collect all subsequent voiding's. The last sample collected should be the first morning specimen voided the following morning at the same time as the previous morning's first voiding.
Specify 24-hour total volume on container and test requisition.

Patient Preparation

N/A

Storage

N/A

Transport Temperature

Refrigerated (cold packs)

Specimen Stability

Room temperature: 8 hours
Refrigerated: 30 days
Frozen: 60 days

Limitations

N/A

Other Acceptable Specimens

N/A

Unacceptable Specimens

Received room temperature • Acidified urine

Order Code

CIT24

EPIC (Premier) Code

LAB5941

Includes

CPT code 81050 may be added at an additional charge for volume measurement

CPT Code

82507 - ** This test is not available for New York patient testing **

Billing Code

670387
500002

CPT Statement

Methodology

Spectrophotometry (SP)

FDA Status

This test was developed and its analytical performance characteristics have been determined by Quest Diagnostics. It has not been cleared or approved by the U.S. Food and Drug Administration. The FDA has determined that such clearance or approval is not necessary. This assay has been validated pursuant to the CLIA regulations and is used for clinical purposes.

Physician Attestation of Informed Consent

N/A

Testing Laboratory

Quest Diagnostics Nichols Institute
14225 Newbrook Drive
Chantilly VA, 20153

Department

Reference Testing

Reference Range

100-1300 mg/24 h

Setup Schedule / Expected Turnaround Time

Sunday - Thursday; Report available: 1 - 3 days