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HelpEpic Test Code LAB21052 Cystinuria Profile, Quantitative, 24 Hour, Urine
Additional Codes
MML Code: CYSQN
NY State Approved
YesPerforming Laboratory
Mayo Clinic Laboratories in Rochester
Reporting Name
Cystinuria Profile, QN, 24 hourMethod Name
Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Urine | Frozen (preferred) | 70 days | |
| Refrigerated | 14 days |
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
-Urine Tubes, 10 mL (T068)
-Diazolidinyl Urea (Germall) 5.0 mL (T822)
Specimen Volume: 5 mL
Collection Instructions:
1. Collect before intravenous pyelogram.
2. Add 5 g of diazolidinyl urea (Germall) as preservative at start of collection. If preservative is not available, refrigerate during collection.
3. Collect urine for 24 hours.
4. Mix well before taking 5-mL aliquot.
Additional Information: See Urine Preservatives-Collection and Transportation for 24-Hour Urine Specimens for multiple collections.
Specimen Type
UrineSpecimen Minimum Volume
1 mL
Reference Values
Cystine
3-15 years: ≤53 mcmol/24 h
≥16 years: ≤115 mcmol/24 h
Lysine
3-15 years: ≤140 mcmol/24 h
≥16 years: ≤290 mcmol/24 h
Ornithine
3-15 years: ≤16 mcmol/24 h
≥16 years: ≤70 mcmol/24 h
Arginine
3-15 years: ≤25 mcmol/24 h
≥16 years: ≤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
Report Available
3 to 5 daysDay(s) Performed
Monday through Friday
CPT Code Information
82136
Reject Due To
All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.Useful For
Diagnosis of cystinuria using 24-hour urine collections
Special Instructions
Disease States
- Cystinuria
Genetics Test Information
This test provides a biochemical diagnosis of cystinuria through the measurement of cystine, lysine, ornithine, and arginine.
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 the short arm of chromosome 2 and SLC7A9 on the long arm of chromosome 19. Initially, the disease was classified into subtypes I, II, and III (type II and III are also referred as non-type 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.
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 non-type 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.
Cautions
No significant cautionary statements
Specimen Retention Time
2 weeksForms
If not ordering electronically, complete, print, and send a Biochemical Genetics Test Request (T798) with the specimen.