Cystinuria Profile, Quantitative, 24 Hour, Urine
NY State Approved Indicates the status of NY State approval and if the test is orderable for NY State clients.
Diagnosis of cystinuria
Genetics Test Information Provides information that may help with selection of the correct test or proper submission of the test request
Diagnosing cystinuria. Measures cystine, lysine, ornithine, and arginine. Add toluene preservative at start of collection.
Special Instructions and Forms Describes specimen collection and preparation information, test algorithms, and other information pertinent to test. Also includes pertinent information and consent forms to be used when requesting a particular test
Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)
Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name
Cystinuria Profile, QN, 24 hour
Cystine, Quantitative, Urine (order when client indicates 24 hr TV)
Cystine, Quantitative, Urine (order when client indicates 24 hr TV)
Specimen Type Describes the specimen type needed for testing
Specimen Required Defines the optimal specimen. This field describes the type of specimen required to perform the test and the preferred volume to complete testing. The volume allows automated processing, fastest throughput and, when indicated, repeat or reflex testing.
Container/Tube: Plastic, 10-mL urine tube (Supply T068)
Specimen Volume: 5 mL
1. Collect before intravenous pyelogram.
2. Collect urine for 24 hours.
3. Add 20 mL of toluene as preservative at start of collection. If toluene is not available, refrigerate during collection.
4. Mix well before taking 5-mL aliquot.
1. 24-Hour volume is required.
2. See Urine Preservatives in Special Instructions for multiple collections.
Forms: New York Clients-Informed consent is required. Please document on the request form or electronic order that a copy is on file. An Informed Consent for Genetic Testing (Supply T576) is available in Special Instructions.
Urine Preservative Collection Options
50% Acetic Acid
Specimen Minimum Volume Defines the amount of specimen required to perform an assay once, including instrument and container dead space. Submitting the minimum specimen volume makes it impossible to repeat the test or perform confirmatory or perform reflex testing. In some situations, a minimum specimen volume may result in a QNS (quantity not sufficient) result, requiring a second specimen to be collected.
Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Cystinuria is an inborn error of metabolism resulting from poor absorption and reabsorption of the amino acid cystine in the intestine and in the kidney. 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, presence of blood in the urine (hematuria), and 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 7,000.
Cystinuria can be classified into 3 subtypes based on the excretion of amino acids in the urine of heterozygotes (parents or children of affected individuals). Heterozygotes of type I excrete normal amounts of cystine, while those with types II and III present with slight to moderate excretion of cystine and other amino acids (lysine, arginine, and ornithine). All 3 subtypes are caused by mutations in only 2 genes, SLC3A1 on chromosome 2p and SLC7A9 on chromosome 19q. A new classification system has been proposed to distinguish the various forms of cystinuria: type A, due to mutations in the SLC3A1 gene; type B, due to mutations in the SLC7A9 gene; and type AB, due to 1 mutation in each SLC3A1 and SLC7A9.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
3-15 years: 11-53 mcmol/24 hours
> or =16 years: 28-115 mcmol/24 hours
3-15 years: 19-140 mcmol/24 hours
> or =16 years: 32-290 mcmol/24 hours
3-15 years: 3-16 mcmol/24 hours
> or =16 years: 5-70 mcmol/24 hours
3-15 years: 10-25 mcmol/24 hours
> or =16 years: 13-64 mcmol/24 hours
Result in mcmol/24 hours x 0.24=result in mg/24 hours
Result in mg/24 hours x 4.17=result in mcmol/24 hours
Homozygotes or compound heterozygotes with cystinuria excrete large amounts of cystine in urine, but the amount varies markedly. Urinary excretion of other dibasic amino acids (arginine, lysine, and ornithine) are 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: the former secretes large amounts of cystine and all 3 dibasic amino acids, whereas the latter secretes more lysine and cystine than arginine and ornithine.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
No significant cautionary statements.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
1. Knoll T, Zollner A, Wendt-Nordahl G, et al: Cystinuria in childhood and adolescence: recommendations for diagnosis, treatment, and follow-up. Pediatr Nephrol 2005 January;20(1):19-24
2. Cystinuria. In The Metabolic and Molecular Bases of Inherited Disease. Eighth edition. Edited by CR Scriver, AL Beaudet, WS Sly, et al. New York, McGraw-Hill Book Company, 2001, pp 4909-4932
Method Description Describes how the test is performed and provides a method-specific reference
Quantitative analysis of the amino acids (AA) 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 (API 3200). 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). Chromatography is performed using a C18 (150x4.6mm) column and total analysis time is 18 minutes.(Lacey JM, Casetta B, Daniels SB, et al: Quantitation in plasma, urine and CSF by Itraq reagent amino acid analysis kit and MS-MS. J Am Soc Mass Spec 2008;19:S97)
Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.
Monday through Friday; 8 a.m.
Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.
3 days (not reported on Saturday or Sunday)
Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result
Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location The location of the laboratory that performs the test
Test Classification Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer's instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR), Investigation Use Only (IUO) product, or a Research Use Only (RUO) product.
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.
CPT Code Information Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Medical Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
LOINC® Code Information Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the result codes returned for this test or profile.
|Result ID||Reporting Name||LOINC Code|