Serum muscle enzyme levels are usually elevated in patients with untreated polymyositis and dermatomyositis. Creatine kinase is the muscle enzyme most often used to diagnose inflammatory myopathies. Seven patients with dermatomyositis and normal creatine kinase levels are described. Five of the seven patients had either an associated malignancy or severe interstitial lung disease. The one-year survival of the six patients followed for that length of time was 33 percent. A lack of creatine kinase elevation in patients with dermatomyositis is a poor prognostic sign.
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