The effect of hydrocortisone on the serum creatine kinase activity of muscles diseases.

Intravenous administration of a single dose of hydrocortisone to patients with the Duchenne type of progressive muscular dystrophy, carriers of Duchenne dystrophy gene caused a short-lasting rise of the serum creatine kinase activity. Administration of hydrocortisone also raised the serum CPK activity in some carriers with a primarly normal CPK level. This phenomenon was observed, though to a lower degree, in limb-girdle muscular dystrophy. The serum CPK activity was sometimes increased after hydrocortisone administration in patients with polymyositis and Kugelberg-Welander spinal muscular atrophy. This phenomenon was never observed in the control group or in cases of myotonic dystrophy. The mechanism of this effect of hydrocortisone on the CPK level is still unknown.