Serum creatine kinase in patients with rheumatic diseases

creatine kinase (CK) activity is reduced in some conditions, including rheu matic diseases, but the aetiology and significance remain to be clarified. The aim of this study was to investigate relationships between serum CK act ivity and other muscle enzymes, muscle mass, renal function, steroid use an d disease activity in patients with rheumatic diseases. Serum CK activity w as measured in sera from 498 patients with rheumatic diseases: rheumatoid a rthritis (RA, n = 145), systemic lupus erythematosus (SLE, n = 31), spondyl oarthropathies (SpA, n = 35), polyarthralgia/arthritis (Poly, n = 74), misc ellaneous group (MI, n = 46), and in non-inflammatory arthropathies (NIA, n = 167) as controls. Serum CK level was significantly reduced in RA (45.4 /- 1.9 IU/l), SLE (46.4 +/- 4.2 IU/l), SpA (64.7 +/- 5.6 IU/l) and MT. (63. 4 +/- 4.8 IU/l), but not in poly (70.2 +/- 3.1 IU/l), compared to controls (78.9 +/- 2.4 IU/l) (P < 0.05). CK values correlated with aspartate aminotr ansferase (AST), erythrocyte sedimentation rate (ESR), body mass index (BMI ) and platelets (Plat) in RA; ESR and haemoglobin (Hb) in SLE, AST, ESR and Hb in SpA; lactate dehydrogenase (LDH), AST, ESR and Hb in Poly; LDH, AST, ESR, Hb and Ccr in MI; and LDH, AST and ESR in controls. In all patients w ith rheumatic diseases CK level was significantly correlated with LDH, AST, alanine aminotransferase (ALT), ESR, C-reactive protein (CRP) and BMI and prednisolone dose, but not with Ccr, age and disease duration. In conclusio n, our data support the possibility that reduced CK activity is inversely c orrelated with inflammatory activity and correlated with other muscle enzym es, muscle mass Abstract: Serum and steroid use, but not with renal functio n, age and disease duration in rheumatic diseases.