[Differential diagnosis of creatine kinase elevation: hypothyroid myopathy (author's transl)].

An increase of creatine kinase (CK) activity in serum as a result of myopathy of skeletal muscle can point to hypothyroidism. In the differential diagnosis from myocardial infarction determination of CK isoenzymes is the most suitable test. In three women (aged 56, 70 and 72 years) with hypothyroid myopathy demonstrated in this manner, administration of thyroid hormone preparations normalised CK activity within 2-4 weeks. A little later thyroid hormone levels in serum were also normal, while histological changes in the musculature persisted rather longer.