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HelpEpic Code LAB848 Cystinuria Profile, Quantitative, 24 Hour, Urine
Additional Codes
Mayo Code: CYSQN
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Useful For
Diagnosis of cystinuria
Specimen Type
UrineSpectrum Health does not stock toluene as a preservative. Refrigeration during and after urine collection is an acceptable means of urine preservation.
Necessary Information
1. 24-Hour volume (in milliliters) is required.
2. Patient's age is required.
3. Include family history, clinical condition (asymptomatic or acute episode), diet, and drug therapy information.
Specimen Required
Supplies: Urine Tubes, 10 mL (T068)
Specimen Volume: 5 mL
Collection Instructions:
1. Collect before intravenous pyelogram.
2. Collect urine for 24 hours.
3. Add 20 mL of toluene as preservative at start of collection. If preservative is not available, refrigerate during collection.
4. Mix well before taking 5-mL aliquot.
Additional Information: See Urine Preservatives-Collection and Transportation for 24-Hour Urine Specimens for multiple collections.
Special Instructions
Specimen Minimum Volume
1 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Urine | Frozen (preferred) | 70 days | |
| Refrigerated | 14 days |
Reject Due To
All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.Day(s) Performed
Monday through Friday
Reference Values
CYSTINE
3-15 years: 11-53 mcmol/24 h
≥16 years: 28-115 mcmol/24 h
LYSINE
3-15 years: 19-140 mcmol/24 h
≥16 years: 32-290 mcmol/24 h
ORNITHINE
3-15 years: 3-16 mcmol/24 h
≥16 years: 5-70 mcmol/24 h
ARGININE
3-15 years: 10-25 mcmol/24 h
≥16 years: 13-64 mcmol/24 h
Conversion Formulas:
Result in mcmol/24 hours x 0.24=result in mg/24 h
Result in mg/24 hours x 4.17=result in mcmol/24 h
Clinical Information
Cystinuria is an inborn error of metabolism resulting from poor absorption and reabsorption of the amino acid cystine in the intestines and kidneys. This leads to an accumulation of poorly soluble cystine in the urine and results in the production of kidney stones (urolithiasis). Symptoms may include acute episodes of abdominal or lower back pain and the presence of blood in the urine (hematuria). Recurrent episodes of kidney stones may result in frequent urinary tract infections, which may ultimately result in renal insufficiency. The combined incidence of cystinuria has been estimated to be 1 in 7000.
Cystinuria is an autosomal recessive disease, but some heterozygous carriers have an autosomal dominant, incomplete penetrance appearance with elevated, but typically nondisease-causing, urinary cystine excretion. Cystinuria is caused by variants in genes, SLC3A1 on chromosome 2p and SLC7A9 on chromosome 19q. Initially, the disease was classified into subtypes I, II, and III (type II and III are also referred as nontype-I) based on the amount of urinary cystine excreted in heterozygous parental specimens. A new classification system has been proposed to distinguish the various forms of cystinuria: type A, due to variants in the SLC3A1 gene; type B, due to variants in the SLC7A9 gene; and type AB, due to 1 variant in each SLC3A1 and SLC7A9 gene.
Cautions
No significant cautionary statements
Interpretation
Individuals who are homozygous or compound heterozygous for cystinuria excrete large amounts of cystine in urine, but the amount varies markedly. Urinary excretion of other dibasic amino acids (arginine, lysine, and ornithine) is also typically elevated. Plasma concentrations are generally normal or slightly decreased.
Individuals who are homozygous and heterozygous for nontype I cystinuria can be distinguished by the pattern of urinary amino acids excretion: homozygous individuals secrete large amounts of cystine and all 3 dibasic amino acids, whereas heterozygous individuals secrete more lysine and cystine than arginine and ornithine.
Reporting Name
Cystinuria Profile, QN, 24 hourMethod Name
Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)
Method Description
Quantitative analysis of the amino acids cystine, lysine, arginine, and ornithine is performed by liquid chromatography tandem mass spectrometry (LC-MS/MS) by labeling amino acids present in urine with aTRAQ Reagent 121. Samples are dried and reconstituted with aTRAQ Reagent 113-labeled Standard Mix. Amino acids are separated and detected by LC-MS/MS. The concentrations of amino acids are established by comparison of their ion intensity (121-labeled amino acids) to that of their respective internal standards (113-labeled amino acids).(Unpublished Mayo method)
CPT Code Information
82136
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| CYSQN | Cystinuria Profile, QN, 24 hour | 90785-7 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| TM38 | Collection Duration | 13362-9 |
| VL36 | Urine Volume | 3167-4 |
| 3583 | Cystine | 13966-7 |
| 3589 | Lysine | 25464-9 |
| 3590 | Ornithine | 25491-2 |
| 3591 | Arginine | 25322-9 |
| 50447 | Reviewed By | 18771-6 |
Report Available
3 to 5 daysTest Classification
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.Clinical Reference
1.Saravakos P, Kokkinou V, Giannatos E. Cystinuria: current diagnosis and management. Urology. 2014;83(4):693-699
2.Servais A, Thomas K, Strologo LD, et al. Cystinuria: clinical practice recommendation. Kidney Int. 2021;99(1):48-58
3.Palacin M, Goodyer P, Nunes V, Gasparini P. Cystinuria. In: Valle DL, Antonarakis S, Ballabio A, Beaudet AL, Mitchell GA, eds. The Online Metabolic and Molecular Bases of Inherited Disease. McGraw Hill; 2019. Accessed March 08, 2023. Available at https://ommbid.mhmedical.com/content.aspx?bookid=2709§ionid=225555540
Forms
If not ordering electronically, complete, print, and send a Biochemical Genetics Test Request (T798) with the specimen.