C4 Acylcarnitine, Quantitative, Random, Urine
Use
Evaluation of patients with abnormal newborn screens showing elevations of iso-/butyrylcarnitine to aid in the differential diagnosis of short‑chain acyl‑CoA dehydrogenase and isobutyryl‑CoA dehydrogenase deficiencies. Elevated iso‑/butyrylcarnitine (C4) in plasma or newborn screening blood spots is due to either SCAD (short‑chain acyl‑CoA dehydrogenase) deficiency or IBD (isobutyryl‑CoA dehydrogenase) 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.
Special Instructions
Not provided.
Limitations
The results of urine acylcarnitines are typically not informative when the patient is receiving L‑carnitine supplements. Almost all patients with isobutyryl‑CoA dehydrogenase deficiency excrete an abnormal amount of iso‑/butyrylcarnitine (C4) in their urine. Some, but not all, affected individuals also excrete elevated levels of isobutyrylglycine. Conversely, patients with short‑chain acyl‑CoA dehydrogenase deficiency can have a normal excretion of C4.
New York Approved
Methodology
Mass Spectrometry (LC‑MS/MS)
Biomarkers
C4 Acylcarnitine
Analyte
LOINC Codes
- 53111-1 - Butyrylcarn/Creat Ur-sRto
- 53111-1 - Butyrylcarn/Creat Ur-sRto
- 59462-2 - Clinical biochemist review
- 18771-6 - Provider signing name
Result Turnaround Time
2-5 days
Related Documents
For more information, please review the documents below
Specimen
Urine
Volume
5 mL
Minimum Volume
1 mL
Container
Plastic, 10 mL urine tube
Collection Instructions
Collect a random urine specimen. Freeze specimen immediately.
Patient Preparation
Discontinue L‑carnitine supplementation at least 72 hours before collection, if clinically feasible.
Stability Requirements
| Temperature | Period |
|---|---|
| Refrigerated | 24 hours |
| Frozen | 7 days |