Hypokalemia-Induced Rhabdomyolysis with Coexisting Hypomagnesemia: A Case Report.

A 69-year-old female was admitted to our hospital due to muscle weakness and gait disturbance. She noted weight loss attributed to inadequate dietary intake and alcohol use approximately 4 months prior. The laboratory findings were as follows: K 2.9 mEq/L, Ca 3.7 mg/dL, Alb 2.4 mg/dL and creatine kinase (CK) 3,986 U/L. Muscle magnetic resonance imaging (MRI) demonstrated abnormal signals in the proximal lower limb muscles. Hypokalemia-induced rhabdomyolysis was suspected. However, her hypokalemia was initially refractory to potassium replacement. Further examination revealed hypomagnesemia (Mg 1.6 mg/dL), and thus oral magnesium supplementation was given alongside potassium. Afterward, the patient's clinical symptoms and electrolyte disorders normalized within10 days; her muscle weakness and myalgia with elevated levels of CK also resolved. Thus, the hypokalemia-induced rhabdomyolysis in this patient was attributed to the coexisting magnesium deficiency. Electrolyte abnormalities and trace element deficiencies can be complicated by states of malnutrition. Awareness of hypomagnesemia may be of crucial importance for the management of hypokalemia-induced rhabdomyolysis. This case report suggests that hypomagnesemia can worsen hypokalemia-induced rhabdomyolysis in patients with impaired nutritional status. Therefore, careful monitoring of electrolytes is required in patients with unusual rhabdomyolysis.