Cystine, Quantitative, Urine

CPT: 82131
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Special Instructions

The test request form must state date and time collection started and finished. The test request form must state whether patient is taking penicillamine or tiopronin or captopril. Measure and record the total 24-hour urine volume on the test request form.


Expected Turnaround Time

4 - 6 days


Related Documents


Specimen Requirements


Specimen

Urine (24-hour)


Volume

5 mL aliquot


Minimum Volume

2.5 mL aliquot (Note: This volume does not allow for repeat testing.)


Container

Plastic urine container without preservative (preferred). 6N HCl or 1g/L Boric acid may be added as a preservative, but may adversely impact other tests for kidney stones or urinalysis.


Collection

24-hour urine: 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). The urine container may be kept at room temperature or refrigerated during collection. Measure and record total urine volume. Mix well, aliquot, and freeze the aliquot for storage and shipping. Label container with patient's name, date of birth, date and time collection started, and date and time collection completed.


Storage Instructions

After aliquoting, specimens should immediately be frozen and maintained frozen during shipping as well as at the testing facility until tested.


Causes for Rejection

Receipt of non-frozen sample


Test Details


Use

Measures levels of cystine in urine to detect presence of cystinuria and nephrolithiasis.


Limitations

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 or 1g/L Boric acid may be added as a preservative, but may adversely impact other tests for kidney stones or urinalysis.

This test was developed and its performance characteristics determined by Labcorp. It has not been cleared or approved by the Food and Drug Administration.


Methodology

Liquid chromatography/tandem mass spectrometry (LC/MS-MS)


Reference Interval

2.1−58.0 mg/24 hours


LOINC® Map

Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
700195 Cystine, Quant. 24 hr Urine 700381 Cystine, Quantitative, Urine mg/L 32169-5
700195 Cystine, Quant. 24 hr Urine 700382 Cystine, Quant, Ur mg/24 hr 2179-0

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