Recurrent limb weakness in a 17-year-old boy.

Wilson disease is a relatively rare inherited disorder of copper accumulation and toxicity, caused by a defect in an enzyme that is part of the pathway of biliary excretion of excess copper. A 17-year-old boy presented with numerous episodes of hypokalemic weakness of the lower limbs of undetermined etiology since 12 years of age. Clinically, lower-motor neuron type of weakness of the limbs with preserved reflexes and paucity of sensory abnormalities were prominent. The investigations revealed distal renal tubular acidosis, hepatitis, and bilateral Kayser-Fleischer ring. The diagnosis of Wilson disease was confirmed by the demonstration of low serum ceruloplasmin, high serum copper, and high urinary copper excretion per se and after penicillamine challenge. He responded satisfactorily to penicillamine and zinc. Careful search of an underlying etiology in children presenting with hypokalemic weakness of the limbs in the face of metabolic acidosis and unexplained hepatitis may reveal Wilson disease.