Exertional rhabdomyolysis in a patient with calcium adenosine triphosphatase deficiency.

A patient with exertional rhabdomyolysis and continuously elevated serum creatine kinase (CK) was investigated. The known causes of recurrent attacks of rhabdomyolysis were ruled out by appropriate histochemical and biochemical investigations. During ischaemic exercise tests an abnormal K(+)-efflux from exercising muscles was observed. The patient was found to have a deficiency of muscular Ca(2+)-ATPase. Dantrolene sodium therapy gave relief of muscle symptoms and improved the exercise tolerance. Both the CK level and the K(+)-efflux in ischaemic forearm testing became normal on this therapy.