Acute myopathy in a patient with oesophageal stricture.

BACKGROUND Muscle injury may be caused by any one of a number of factors, including trauma, drugs, hyperthermia and metabolic derangement. Symptoms and signs are often non-specific, and myopathy may be easily overlooked. CASE An elderly woman was referred to hospital for investigation of rapidly declining mobility in the setting of anorexia and vomiting due to benign oesophageal stricture. The patient had generalised muscle weakness and tenderness. Investigations showed severe metabolic alkalosis and hypokalaemia, and creatinine kinase (CK) activity was grossly elevated at 40,000 U/l. OUTCOME CK activity remained elevated for several days, and a diagnosis of polymyositis was considered. However, muscle tenderness resolved and CK activity declined after correction of the underlying metabolic disturbances. Acute myopathy was attributed to hypokalaemia. CONCLUSIONS Hypokalaemia is an important cause of acute myopathy, and older patients may present with non-specific symptoms. A high degree of clinical suspicion is needed to establish the diagnosis. The clinical features and the pathogenes of hypokalaemia-induced myopathy are reviewed.