Use

The C5-OH Acylcarnitine test is useful for evaluating patients with abnormal newborn screens showing elevations of 3-hydroxyisovaleryl-/2-methyl-3-hydroxybutyryl-carnitine. Elevated levels of C5-OH in plasma or newborn screening blood spots can indicate several biochemical genetic diagnoses, including 3-methylcrotonylglycinuria, 3-hydroxy 3-methylglutaryl-CoA lyase deficiency, beta-ketothiolase deficiency, 2-methyl 3-hydroxybutyryl-CoA dehydrogenase deficiency, 3-methylglutaconic aciduria, biotinidase deficiency, or holocarboxylase deficiency. Measuring urine C5-OH is particularly useful in differentiating between 3-methylcrotonylglycinuria and 3-methylglutaconic aciduria, as these conditions typically result in larger amounts of C5-OH excretion in urine.