Response of serum creatine phosphokinase to steroid hormone.

Serum creatine phosphokinase activity increased significantly four or six hours after the administration of prednisolone in patients with muscular dystrophy of various types, whereas it did not increase in other muscular disorders. The extent of the response correlated inversely with the grade of disability. The prednisolone test may help to differentiate muscular dystrophy from polymyositis.