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HelpTest ID C5OHU C5-OH Acylcarnitine, Quantitative, Urine
Useful For
Evaluation of patients with an abnormal newborn screen showing elevations of 3-hydroxyisovaleryl-/2-methyl-3-hydroxybutyryl-carnitine (C5-OH)
Special Instructions
Method Name
Flow Injection Analysis-Tandem Mass Spectrometry (FIA-MS/MS)
Reporting Name
C5-OH Acylcarnitine, QN, USpecimen Type
UrineCollection Container/Tube: Clean, plastic urine collection container
Submission Container/Tube: Plastic, 10-mL urine tube (T068)
Specimen Volume: 5 mL
Collection Instructions:
1. Collect a random urine specimen.
2. Freeze specimen immediately.
Additional Information: Include patient's age, family history, clinical condition (asymptomatic or acute episode), diet, and drug therapy information.
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 (T576) is available in Special Instructions.
Specimen Minimum Volume
1 mL
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Urine | Frozen (preferred) | 7 days |
| Refrigerated | 24 hours |
Clinical Information
The differential diagnosis of an isolated elevation of 3-hydroxyisovaleryl-/2-methyl-3-hydroxy acylcarnitine (C5-OH) in plasma or (newborn screening) blood spots includes the following disorders:
-3-Methylcrotonyl-CoA carboxylase deficiency (common name: 3-methylcrotonylglycinuria), either infantile or maternal
-3-Hydroxy 3-methylglutaryl-(HMG)-CoA lyase deficiency
-Beta-ketothiolase deficiency
-2-Methyl 3-hydroxybutyryl-CoA dehydrogenase deficiency, 3-methylglutaconic aciduria type I, and biotinidase deficiency or holocarboxylase deficiency
Confirmatory and diagnostic testing are necessary to differentiate these clinical entities. This test can be useful in differentiating patients with 3-methylcrotonylglycinuria and with 3-methylglutaconic aciduria as they typically excrete larger amounts of C5-OH in urine compared to patients with the other diagnoses.
The American College of Medical Genetics (ACMG) newborn screening work group published diagnostic algorithms for the follow-up of infants who had positive newborn screening results. For more information, see URL: http://www.acmg.net.
Reference Values
<2.93 millimoles/mole creatinine
Cautions
The results of urine acylcarnitines are not informative when the patient is receiving L-carnitine supplements.
Day(s) Performed
Monday, Wednesday, Friday
Report Available
2 days (not reported on Sunday)Performing Laboratory
Mayo Medical Laboratories in Rochester
Test Classification
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
82017