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Order Code C5DCU C5-DC Acylcarnitine, Quantitative, Random, Urine

Reporting Name

C5-DC Acylcarnitine, QN, U

Useful For

Evaluation of patients with an abnormal newborn screen showing elevations of glutarylcarnitine

 

Diagnosis of glutaric aciduria type 1 deficiency

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Specimen Type

Urine


Ordering Guidance


This second-tier test is used specifically to evaluate a newborn screening elevation of glutarylcarnitine and must not be ordered with either C4U / C4 Acylcarnitine, Quantitative, Random, Urine or C5OHU / C5-OH Acylcarnitine, Quantitative, Random, Urine.

 

For general screening for metabolic disorders, see OAU / Organic Acids Screen, Random, Urine; ACRN / Acylcarnitines, Quantitative, Plasma; and AAQP / Amino Acids, Quantitative, Plasma.



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

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 Special Container
Urine Frozen (preferred) 7 days
  Refrigerated  24 hours

Reference Values

<1.54 millimoles/mole creatinine

Day(s) Performed

Monday, Wednesday, Friday

CPT Code Information

82017

Genetics Test Information

Elevated glutarylcarnitine (C5-DC) in plasma or newborn screening blood spots is due to glutaric aciduria type 1 (GA-1), also known as glutaric acidemia type 1.

 

Urine C5-DC is a biochemical marker of GA-1 that appears to be elevated even in low excretors, who are affected patients with normal levels of glutaric acid in urine.

Method Description

Acylcarnitines, including glutarylcarnitine, are determined in urine by flow injection analysis tandem mass spectrometry using acetyl-d3-carnitine, propionyl-d3-carnitine, butyryl-d3-carnitine, octanoyl-d3-carnitine, dodecanoyl-d3-carnitine, and palmitoyl-d3-carnitine as internal standards. The supernatant is evaporated and the residue treated with n-butanolic hydrochloric acid yielding the acylcarnitines for analysis as their n-butyl esters.(Tortorelli S, Hahn SH, Cowan TM, et al. The urinary excretion of glutarylcarnitine is an informative tool in the biochemical diagnosis of glutaric acidemia type I. Mol Genet Metab. 2005;84(2):137-143; Miller MJ, Cusmano-Ozog K, Oglesbee D, Young S; ACMG Laboratory Quality Assurance Committee. Laboratory analysis of acylcarnitines, 2020 update: a technical standard of the American College of Medical Genetics and Genomics (ACMG). Genet Med. 2021;23(2):249-258)

Reject Due To

  All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.

Method Name

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