Cystine, 24-Hour Urine, Quantitative

Test Codes

EPIC: LAB1231980, Beaker: CYSTINE24, Quest: 10947

Department

Send Outs

Instructions

• Use for monitoring treatment of patients previously diagnosed with cystinuria.
• A Urine Creatinine test is performed on each sample.
• Please refer to the Specimen Collection Manual for instructions on 24 Hour Urine Collection:
  • Urine 24-Hour Collection - Inpatient.
  • Urine 24-Hour Collection - Outpatient.
  • Urine 24-Hour Collection - Outreach.

Specimen Collection Criteria

Collect: 24-hour urine sample with no preservative.

• Keep 24-hour urine specimen iced or refrigerated during collection.
• Include start and end dates and times for the collection period on the specimen container.
• Start collection after first morning void. Collect through first morning void of the next day.
• Critical frozen. Specimens must be delivered to the Laboratory immediately after completion of collection.

Physician Office/Draw Specimen Preparation

Maintain specimens, refrigerate (2-8°C or 36-46) prior to transport.

Preparation for Courier Transport

Transport: Entire 24-hour urine collection, frozen (-20°C/-4°F or below).

Rejection Criteria

• Random urine samples.
• Urine with any type of preservative.
• pH <2.0.
• IVP within 48 hours of collection.
• Received room temperature.
• Received refrigerated.
• Specimens not collected and processed as indicated.

In-Lab Processing

Measure total volume of 24-hour urine specimen. Record total volume and collection start and end dates and times in the LIS system. Aliquot 1.8 mL from the well-mixed 24-hour urine collection and freeze (-20°C/-4°F or below). (Minimum: 0.6 mL)

Transport: 1.8 mL aliquot of 24-hour urine, frozen (-20°C/-4°F or below). (Minimum: 0.6 mL)

Storage

Specimen Stability for Testing:

Room temperature (20-26°C or 68-78.8°F): Unacceptable
Refrigerated (2-8°C or 36-46°F): 48 hours
Frozen (-20°C/-4°F or below): 28 days

Specimen Storage in Department Prior to Disposal:

Specimen retention time is determined by the policy of the reference laboratory. Contact the Send Outs Laboratory with any questions.

Laboratory

Sent to Quest Diagnostics, Wood Dale, IL.

Performed

Tuesday, Thursday.
Results available in 4-10 days.

Reference Range

Pediactric
0-9 Years                6-48 umol/24 hrs
10-13 Years          10-94 umol/24 hrs
14-17 Years        17-102 umol/24 hrs
Adults                 12-184 umol/24 hrs

Test Methodology

Chromatography/Mass Spectrometry

Clinical Utility

Cystine, 24-Hour Urine – This quantitative test may be useful in the diagnosis and monitoring of cystinuria [1,2]. For diagnostic evaluation, this test may be ordered for individuals with clinical suspicion of cystinuria, including those who have symptoms of kidney stones or cystine crystals detected in urinalysis [2]. This test can also help monitor the effectiveness of treatment for individuals with cystinuria [2].

Cystinuria, an autosomal recessive genetic disorder that can cause kidney stones, is characterized by excessive excretion of cystine and dibasic amino acids in the urine. Around 1% to 2% of all kidney stones, and 6% to 8% of kidney stones in children, are caused by cystinuria [1]. Approximately 83% of patients with cystinuria who develop a kidney stone will have a recurrence within 5 years [2]. Common complications of cystinuria include chronic kidney disease and hypertension [2].

This test does not differentiate between free and bound cystine in patients taking cystine-binding thiol drugs [1]. This test alone is not sufficient to predict risk of kidney stones in individuals with cystinuria [1,2]. For young children when 24-hour urine collection is not possible, measurement of cystine concentration per gram of creatinine in the first-morning urine may be helpful as part of the diagnostic evaluation [1].

The results of this test should be interpreted in the context of pertinent clinical and family history and physical examination findings.

Reference

1. Leslie SW, et al. Cystinuria. In: StatPearls [Internet]. StatPearls Publishing; 2022. Accessed June 16, 2022. https://www.ncbi.nlm.nih.gov/books/NBK470527/
2. Daga S, et al. Urology. 2021;149:70-75.

CPT Codes

82131

Contacts

Last Updated

11/19/2025