Rhabdomyolysis - may it be a metabolic myopathy? Case report and diagnostic algorithm]

We report the case of a 46-year-old female patient with recurrent rhabdomyolysis. In the background of her metabolic myopathy an inherited metabolic disorder of the fatty acid oxidation, very long-chain acyl-coenzyme A-dehydrogenase deficiency was diagnosed. The diagnosis was based on abnormal acyl-carnitine-and urine organic-acid profile in addition to low residual enzyme activity, and was confirmed by genetic testing. After introduction of dietotherapy metabolic crisis necessitating hospital admission has not occurred neither have fixed myopathic changes developed. We present here the differential diagnosis of rhabdomyolysis and exertional muscle complaints, with the metabolic myopathies in focus. The main features of fatty acid oxidation disorders are highlighted, acute and chronic managements of very long-chain acyl-coenzyme A-dehydrogenase deficiency are discussed. Metabolic myopathies respond well to treatment, so good quality of life can be achieved. However, especially in fatty acid oxidation disorders, a metabolic crisis may develop quickly and can be fatal, albeit rarely. Some of these disorders can be identified by newborn screening, but occasionally the symptoms may manifest only in adulthood. With the presentation of this case we would like to point out that in the differential diagnosis of recurrent rhabdomyolysis inherited metabolic disorders should be considered regardless of the patient's age.