The presence of serum creatine kinase 2 (MB) in hypokalemic familial periodic paralysis.

We recently found 17 U/l of isoenzyme creatine kinase (CK) 2 (MB), or 3.2% of total 533 U/l CK activity, in a patient with hypokalemic familial periodic paralysis who did not show clinical or EKG evidence of acute myocardial necrosis. The myopathy associated with hypokalemic familial periodic paralysis is thus another cause for the presence of CK 2 (MB). CK 2 (MB) is not a specific isoenzyme for myocardial damage since it may be identified in the serum of patients with skeletal muscle conditions.