Serum creatine phosphokinase and pyruvate kinase in neuromuscular disorders and Duchenne dystrophy carriers.

Serum levels of creatine phosphokinase (CPK) and pyruvic kinase (PK) were determined in 42 controls, 57 patients with various neuromuscular disorders, and 23 female relatives of Duchenne dystrophy patients. CPK and PK enzyme activities were increased in comparable numbers of muscle disease patients and female carriers; there was no advantage in the combined use of the two tests. We did not confirm earlier reports suggesting that determination of PK is more valuable than CPK in carrier detection.