Evaluation of patients with an abnormal newborn screen showing elevations of 3-hydroxyisovaleryl-/2-methyl-3-hydroxybutyryl-carnitine (C5-OH)
Evaluation of patients with an abnormal newborn screen showing elevations of C5-OH. The results are not informative when patient is receiving L-carnitine supplements.
- Elevated 3-hydroxyisovaleryl-/2-methyl-3-hydroxy acylcarnitine (C5-OH) in plasma or newborn screening blood spots is due to one of several biochemical genetic diagnoses: 3-methylcrotonylglycinuria, 3-Hydroxy 3-methylglutaryl-(HMG)-CoA lyase deficiency, beta-ketothiolase deficiency, 2-Methyl 3-hydroxybutyryl-CoA dehydrogenase deficiency, 3-methylglutaconic aciduria, biotinidase deficiency or holocarboxylase deficiency.
- Urine C5OH is 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.
- If patient is receiving L-carnitine supplementation, the result of this urine acylcarnitine test will not be informative.
Flow Injection Analysis-Tandem Mass Spectrometry (FIA-MS/MS)
C5-OH Acylcarnitine, QN, U
Hydroxymethylglutaryl-CoA (HMG-CoA) Lyase Deficiency
Multiple Carboxylase Deficiency
3-Methylcrotonyl-CoA Carboxylase Deficiency
3-Methylglutaconic Aciduria Type 1
3-Methylglutaconic Aciduria Type I
3-Methylglutaconyl-CoA Hydratase Deficiency
HMG-CoA (Hydroxymethylglutaryl-CoA) Lyase Deficiency
Holocarboxylase Synthetase Deficiency