Test Directory

This test measures levels of cystine in urine to detect presence of cystinuria and nephrolithiasis.

Specimen Type: 24 Hour Urine

Collection Container: 24 Hour Plastic Urine Container (no preservative)

Desired Specimen Volume: 5 mL

1. Collect a 24-hour urine specimen.
2. The urine container may be kept at room temperature or refrigerated during collection. 

1. Mix well and transfer 5 mL of urine to a LabCorp PP transpak frozen purple tube (s). Freeze immediately.
2. The test request form must state whether patient is taking penicillamine, tiopronin, or captopril.
3. Measure and record total urine volume. Must state date and time collection started and finished.

The test request form must state whether patient is taking penicillamine, tiopronin, or captopril. 

Transport to the laboratory frozen. 

• Receipt of non-frozen sample

 See patient report.

Penicillamine and Tiopronin combine with cystine and lower cystine level in urine. Captopril and other thiol-containing medications/substances may also interfere with this test. 6N HCl may be added as a preservative but may adversely impact other tests for kidney stones or urinalysis.