Serum muscle enzymes, muscle pathology and clinical muscle weakness: correlation in Thai patients with polymyositis/dermatomyositis.

ABSTRACT

The clinical correlation between serum muscle enzymes, muscle pathology and muscle weakness was studied in 100 Thai patients (22 males and 78 females) with polymyositis (PM) and dermatomyositis (DM). Their mean +/- SD age and duration of disease were 45.0 +/- 13.9 years and 6.3 + 13.4 months, respectively. There was idiopathic PM in 37 cases, idiopathic DM in 13, PM/DM associated with malignancy in 5 and PM associated with connective tissue disease in 45. Serum muscle enzymes including creatine phosphokinase, lactate dehydrogenase and aspartate aminotransferase were elevated in 87 per cent, 92 per cent, and 82 per cent of cases, respectively. Abnormal electromyographic findings that were compatible with inflammatory myopathy were found in 76 per cent of cases. Seventy-seven per cent had an abnormal muscle biopsy that was consistent with polymyositis. There was a significant correlation between serum muscle enzymes and muscle pathology (p < 0.01). The degree of muscle weakness correlated better with the degree of muscle destruction (p = 0.01) than the degree of muscle inflammation (p = 0.03). The erythrocyte sedimentation rate showed no correlation with serum muscle enzymes, muscle pathology or muscle weakness.