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Test ID C4U C4 Acylcarnitine, Quantitative, Urine

Useful For

Evaluation of patients with abnormal newborn screens showing elevations of iso-/butyrylcarnitine (C4) to aid in the differential diagnosis of short-chain acyl-CoA dehydrogenase and isobutyryl-CoA dehydrogenase deficiencies

Genetics Test Information

Useful for differentiating the potential diagnoses of short chain acyl-CoA dehydrogenase (SCAD) versus isobutyryl-CoA dehydrogenase deficiency. The results are not informative when patient is receiving L-carnitine supplements.

Highlights

Elevated iso-/butyrylcarnitine (C4) in plasma or newborn screening blood spots is due to either short chain acyl-CoA dehydrogenase (SCAD) deficiency or isobutyryl-CoA dehydrogenase (IBD) deficiency.

 

Urine C4 results can distinguish between SCAD deficiency, which results in normal C4 in urine, and IBD deficiency, which results in elevated C4 in urine.

 

If patient is receiving L-carnitine supplementation, the result of this urine acylcarnitine test will not be informative.

Method Name

Flow Injection Analysis-Tandem Mass Spectrometry (FIA-MS/MS)

Reporting Name

C4 Acylcarnitine, QN, U

Specimen Type

Urine


Necessary Information


Include patient's age, family history, clinical condition (asymptomatic or acute episode), diet, and drug therapy information.

Specimen Required


Patient Preparation: If clinically feasible, discontinue L-carnitine supplementation at least 72 hours before specimen collection.

Supplies: Urine Tubes, 10 mL (T068)

Collection 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.


Specimen Minimum Volume

1 mL

Specimen Stability Information

Specimen Type Temperature Time
Urine Frozen (preferred) 7 days
  Refrigerated  24 hours

Reference Values

<3.00 millimoles/mole creatinine

Day(s) and Time(s) Performed

Monday, Wednesday, Friday; 8:00 a.m.

Performing Laboratory

Mayo Medical Laboratories in Rochester

CPT Code Information

82017

LOINC Code Information

Test ID Test Order Name Order LOINC Value
C4U C4 Acylcarnitine, QN, U In Process

 

Result ID Test Result Name Result LOINC Value
88829 C4 Acylcarnitine, QN, U 53111-1
28075 C4 Interpretation 59462-2
34468 Reviewed By No LOINC Needed

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.

Testing Algorithm

See Newborn Screening Follow-up for Isolated C4 Acylcarnitine Elevations (also applies to any plasma or serum C4 acylcarnitine elevation) in Special Instructions.

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.