High elevations of creatine phosphokinase in hypothyroidism. An isoenzyme analysis
J. Goldman, R. Matz, R. Mortimer and R. Freeman
In hypothyroidism, slight elevations of serum creatine phosphokinase (CPK)
levels are common. In contrast, we describe six hypothyroid patients with
extreme elevations (17- to 160-fold) of CPK levels. Enzyme analysis showed
only MM isoenzyme in four cases and MM plus trace MB isoenzyme in two
patients. Hypothyroidism should, therefore, be considered when elevated CPK
levels, even extreme, are found. Isoenzyme analysis in such a case will
show primarily an MM pattern, although trace MB fraction can also be seen.
This isoenzyme pattern suggests that the sources of the CPK elevations is
skeletal muscle.
