The relation of serum levels of muscle enzymes with clinical findings in rheumatoid arthritis

Abstract

The aim of this study was to evaluate the association of serum levels of muscle enzymes with disease activity measures in patients with rheumatoid arthritis. Twenty-five patients with rheumatoid arthritis (RA) and 16 healthy female controls with comparable age, height, weight and body mass index were enrolled in this study. Serum creatine kinase (CK) and CK-MB, lactic dehydrogenase (LDH) were measured and isoenzyme determination, CK and LDH electrophoresis were performed in all subjects, and those values were compared with disease activity measures (erythrocyte sedimentation rate, CRP, tender joint count and swollen joint count, and pain assessment by visual analogue scale). Subgroup analysis regarding exercise level, serum rheumatoid factor level, corticosteroid use, presence of deformity or swollen joints was also made. Only the CK levels were significantly different (p<0,01). Subgroup analysis revealed a significantly higher LDH5 isoenzyme level in the exercising RA patients. While serum CK levels showed a negative correlation with tender joint count, swollen joint count and pain, serum LDH levels correlated positively with CRP. Serum CK levels may be lower in patients with RA. Hence, if one just relies on the serum CK levels in the patients with RA who also have acute myocardial infarction or inflammatory muscle disease, he may be misleaded.