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January 9, 1978

Creatinine Phosphokinase Levels in Hypothyroidism

Author Affiliations

Henry Ford Hospital Detroit

JAMA. 1978;239(2):107. doi:10.1001/jama.1978.03280290027007

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To the Editor.—  The recent article by Goldman et al (238:325, 1977) on high elevations of creatinine phosphokinase (CPK) levels in hypothyroidism interested us very much. We have encountered two such patients (64-year-old and 60-year-old women) who became hypothyroid following radioactive iodine therapy for Grave's disease. On initial screening both were hypothyroid clinically and biochemically. Serum thyroxine levels were 0.2 μg/dl and 1.2 μg/dl (normal 5 to 11 μg/dl). Serum thyroid stimulating hormone level by radioimmunoassay was >100 μU—l and 50 μU/ml, respectively. In addition, both of them had very high CPK levels (> 2,000 mU/ml and 978 mU/ml, respectively; normal, <190 mU/ml). In one patient it consisted exclusively of MM isoenzyme fractions. Concurrent elevations of lactic dehydrogenase and transaminase levels were also noted. All these abnormalities returned to normal in two or three weeks following replacement therapy. These two patients add to the observation of Goldman et al with