Importance of acylcarnitine profile analysis for disorders of lipid metabolism in adolescent patients with recurrent rhabdomyolysis: Report of two cases.

Metabolic myopathies due to disorders of lipid metabolism are a heterogeneous group of diseases. Newborns may present with hypotonia and convulsions, while progressive proximal muscle weakness or recurrent episodes of muscle weakness accompanied by rhabdomyolysis/myoglobinuria may be seen in older ages. There is little knowledge on detection of disorders of lipid metabolism by acylcarnitine profile (ACP) analysis by tandem mass spectrometry outside the neonatal period particularly in cases with recurrent rhabdomyolysis first presenting in adolescence and adulthood. Two adolescent female cases presented with episodes of rhabdomyolysis and muscle weakness. A 13-year-old patient had five episodes of rhabdomyolysis triggered by infections. Tandem mass spectrometry was normal. A 16-year-old female patient was hospitalized eight times due to recurrent rhabdomyolysis. Increased levels of C14:2, C14:1, and C14 were determined in tandem mass spectrometry. Final diagnoses were carnitine palmitoyltransferase II (CPT II) deficiency and very long-chain acyl-CoA dehydrogenase (VLCAD) deficiency. Increased serum levels of long-chain acylcarnitine can guide to the diagnosis of lipid metabolism disorders. Serum ACP should be performed before enzyme assay and genetic studies.