Chloride, 24-Hour Urine

Casandra

Casandra Test Code LC72502Version 1 (DRAFT)

Performing Lab

Lab LabcorpLab Test ID 003160CPT Code 82436

Chloride, 24-Hour Urine

Clinical Use

Use

This test is used to evaluate the electrolyte composition of urine and for studies on acid-base balance. It helps to distinguish whether a case of metabolic alkalosis is chloride-responsive (salt responsive) or not. By measuring urine chloride levels, it assists in differential diagnosis of metabolic alkalosis, especially in scenarios of chloride depletion, which can often be corrected through chloride repletion. It is also used to identify cases of chloride-resistant conditions such as those caused by endogenous or exogenous corticosteroids, which may require further investigation for potential ACTH or aldosterone producing neoplasms.

Special Instructions

Ensure to state the total 24-hour urine volume on the test request form. Proper collection protocol must be followed to ensure accuracy of results.

Limitations

Halogens other than chloride, such as bromide present in urine, may falsely elevate the chloride results. Without concurrent urine sodium or potassium levels or corresponding serum electrolytes, the isolated urine chloride value might be misleading. The effect of profound potassium depletion on chloride reabsorption can complicate interpretation, and fetal urinary electrolytes are unreliable for assessing fetal renal function.

Test Details

Methodology

Automated Analyzer (Clinical Chemistry)

Biomarkers

Chloride

Analyte

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

LOINC Codes

Order Codes

2079-2

Result Codes

2078-4
2079-2

Result Turnaround Time

1 day

Specimen

Urine

Volume

10 mL aliquot of entire collection

Minimum Volume

0.5 mL aliquot

Container

Plastic urine container, no preservative

Collection Instructions

For a 24-hour collection, instruct patient to void at 8 AM (or 8 PM), and discard the specimen. Then collect all the urine including the final specimen voided at the end of the 24-hour collection period (ie, 8 AM [or 8 PM] the following day). Container must be labeled with patient's name and date and time collection started and finished.