C5-DC Acylcarnitine, Quantitative, Random, Urine

Casandra

Casandra Test Code MC75749Version 1 (DRAFT)

Performing Lab

Lab Mayo Clinic LabLab Test ID C5DCUCPT Code 82017

C5-DC Acylcarnitine, Quantitative, Random, Urine

Clinical Use

Use

Urine glutarylcarnitine (C5‑DC) is a specific biochemical marker for glutaric aciduria type 1 (GA‑1), including in low‑excretor patients with normal urinary glutaric acid levels. This test is useful for evaluating patients with abnormal newborn screens showing elevations of glutarylcarnitine and supports diagnosis of GA‑1 deficiency. GA‑1 is an autosomal recessive disorder of glutaryl‑CoA dehydrogenase, associated with neurologic injury, dystonia, and macrocephaly; early diagnosis allows dietary and acute illness interventions to prevent neurologic injury. Important clinical context—particularly family history, diet, and L‑carnitine supplementation—impacts interpretation.

Special Instructions

This second‑tier test should not be ordered with C4U or C5OHU; intended for follow‑up of newborn screen elevations of glutarylcarnitine. If applicable, discontinue L‑carnitine supplementation at least 72 hours prior to specimen collection. Include patient age, family history, clinical condition, diet, and drug therapy information with the specimen submission. Use Biochemical Genetics Test Request (T798) if not ordering electronically.

Limitations

Urine acylcarnitine results may be affected if the patient is receiving L‑carnitine supplements, which can reduce test informativeness. Analytical performance is based on laboratory‑developed method (FIA‑MS/MS) under CLIA without FDA clearance. All specimens will be evaluated for test suitability upon receipt.

Test Details

New York Approved