A case of recurrent, spontaneous rhabdomyolysis: A manifestation of McArdle disease

Abstract

Background: McArdle Disease is a glycogen storage disease caused by an inherited deficiency in myophosphorylase, an enzyme that initiates the breakdown of muscle glycogen for glycolysis. Due to clinical variability and low prevalence, this disease is often delayed in diagnosis. Patients may present in early adulthood, suffering from exercise intolerance, muscle fatigue, myalgias, and potential end-organ damage from rhabdomyolysis and myoglobinuria. Diagnosis is confirmed with muscle biopsy showing an absence of myophosphorylase activity and can be confirmed with PYGM genetic sequencing. Treatment is preventative through dietary control with the use of complex carbohydrates and the ingestion of simple carbohydrates prior to aerobic activity.Case presentation: A 19-year-old Caucasian male presented with a four-day history of rhabdomyolysis and acute kidney injury triggered by diving into cold water and swimming. The patient had developed muscle spasms and dyspnea, followed by a period of emesis, dysuria, and numbness in the lower extremities. Laboratory tests revealed creatinine kinase levels greater than 100,000 U/L and creatinine of 1.6 mg/dl. The patient had experienced a similar episode three months prior that occurred after sprinting, requiring hospitalization secondary to rhabdomyolysis. After eliminating reversible causes for rhabdomyolysis, there was high clinical suspicion for McArdle Disease, confirmed by muscle biopsy with absent phosphorylase activity. The patient was managed with parenteral fluids to treat the rhabdomyolysis and counseled on preventative dietary and exercise strategies.Conclusions: The late onset of presentation of McArdle Disease should prompt consideration of metabolic myopathies in a systemic evaluation for cases of recurrent rhabdomyolysis.