A B C D E F G H I J K L M N O P Q R S T U V W X Y Z # |
Citric Acid, 24-Hour Urine without Creatinine
Test CodeCPT Codes
82507<br><strong>** This test is not available for New York patient testing.**</strong>
Includes
Preferred Specimen
Minimum Volume
Instructions
Specify 24-hour total volume on container and test requisition.
Transport Temperature
Specimen Stability
Refrigerated: 30 days
Frozen: 60 days
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Methodology
Spectrophotometry (SP)
Setup Schedule
Clinical Significance
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.