Sodium, 24-Hour Urine

Casandra

Casandra Test Code LC48187Version 1 (DRAFT)

Performing Lab

Lab LabcorpLab Test ID 003178CPT Code 84300

Sodium, 24-Hour Urine

Clinical Use

Use

Work up volume depletion, acute renal failure, acute oliguria, and differential diagnosis of hyponatremia.1 Division of hyponatremia into hypervolemia or not, edema or not, and urinary Na+ less than or greater than 10 mmol/L provides a classification of hyponatremia.2 History of diuretics, other drug intake, setting of osmotic diuresis or not, serum or plasma electrolytes and other factors are needed.

Special Instructions

The test request form must include the date and time collection started, date and time collection finished, and total 24-hour urine volume. Ensure the lid is securely screwed on and the container is labeled with the patient's full name and the collection start and end details.

Limitations

This test may face limitations in its applicability for diagnosis when spot urine sodium levels are considered without additional data. Low sodium excretion may appear in early obstructive uropathy, acute glomerulonephritis, and x-ray contrast acute renal failures, while high sodium excretion in oliguria suggests acute tubular necrosis.

Test Details

Methodology

Automated Analyzer (Clinical Chemistry)

Biomarkers

Sodium

Analyte

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

LOINC Codes

Order Codes

2956-1

Result Codes

2955-3
2956-1

Result Turnaround Time

1 day

Specimen

Urine

Volume

10 mL aliquot

Minimum Volume

1 mL aliquot

Container

Plastic urine container without preservative

Collection Instructions

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, date and time collection started, and date and time collection finished.