Serum Creatine Kinase in Progressive Muscular Dystrophies

Several enzymes originating in muscle show increased activity in the serum of patients affected with different forms of muscular dystrophy (MD). These enzymes include creatine kinase (CK), aldolase, transaminase, and pyruvate kinase (PK), among others (reviewed in ref. 1 ). In the premolecular era, determination of serum enzymes represented the only noninvasive method for diagnosis of neuromuscular disorders and estimation of heterozygosity risks in females at risk for Duchenne and Becker muscular dystrophies (DMD/BMD). During many years, the authors’ laboratory measured both serum CK (SCK) and PK in patients affected by different forms of muscular dystrophy (MD) as well as in DMD/BMD potential carriers, compared to normal controls (2 –9 ). Assessment of serum PK activity was an important adjunct test to improve the sensitivity of serum CK, in particular, for carrier detection. However, after the introduction of molecular analysis, determinations of serum PK activity became of little practical use for this purpose.