Adynamia episodica hereditaria

Abstract

A disease designated adynamia episodica hereditaria is described. The disease is inherited as a monohybrid, autosomal dominant with complete or almost complete penetrance. The disorder usually makes its first appearance in childhood. It is characterized by intermittent attacks of paralysis with symptom-free intervals. During the attacks the serum potassium level increases, without any decrease in urinary potassium. Attacks can be provoked by oral administration of 1 to 2.5 gm. of potassium. Electrocardiographic and electromyographic changes are demonstrable during attacks. The motor response to acetylcholine is increased during and between attacks. Premedication with glucose inhibits the provocative effect of potassium salts. Calcium administered intravenously during an attack promptly controls the symptoms. Adynamia episodica hereditaria is undoubtedly a clinical entity. No other disease is known in which the serum potassium level increases spontaneously without decreased excretion of potassium in the urine, and without signs of widespread cellular destruction, and in which oral administration of 1 to 2.5 gm. of potassium is sufficient to precipitate paralysis, with elevation of the serum potassium. The spontaneous increase in serum potassium is probably due to excessive leakage of potassium from the cells. The beneficial effect of glucose administered before an otherwise provocative dose of potassium argues in the same direction.