title: Reduced serum creatine kinase activity in inflammatory rheumatic diseases.
abstract: OBJECTIVE
  To determine if serum CK activity is reduced in inflammatory rheumatic diseases and to evaluate whether this phenomenon is linked to disease activity or steroid therapy.
  
  
  METHODS
  Serum CK activity was measured in patients with systemic lupus erythematosus (SLE, n = 52), rheumatoid arthritis (RA, n = 80), ankylosing spondylitis (AS, n = 82), spondyloarthropathies other than AS (SpA, n = 22), and a miscellaneous group (MI, n = 27), and in 103 control patients with noninflammatory arthropathies (NIA). Laboratory variables of inflammatory activity such as ESR, CRP, platelet count, and hemoglobin (and anti-DNA antibodies and complement levels in SLE) were measured at the same time. Daily dose of steroids was also evaluated.
  
  
  RESULTS
  Serum CK activity was significantly reduced in SLE (mean +/- SD: 49 +/- 41 IU/l), RA (68 +/- 41 IU/l), SpA (88 +/- 53 IU/l), and MI (75 +/- 32 IU/l) compared to controls (111 +/- 38 IU/l) (p = 0.002 for SpA and p < 0.001 for the other groups). No differences in CK values were observed between AS and controls, although AS patients with peripheral arthritis had lower serum CK activity than those without (80 +/- 32 vs 121 +/- 62 IU/l, respectively, p < 0.05. ESR, CRP, and platelets correlated inversely with CK values in RA, AS, and MI. In the SpA group only ESR correlated inversely with CK. In SLE, a positive correlation was found between CK values and CH50 and a negative one with anti-DNA levels. Patients taking steroids had significantly lower CK activity than those without corticotherapy. However, multivariate analysis showed that only inflammatory activity and no steroids had an effect in reducing CK activity.
  
  
  CONCLUSIONS
  Serum CK activity is significantly reduced in several inflammatory rheumatic diseases. Inflammatory activity seems to play the major role in this phenomenon.
authors.affiliation: Department of Rheumatology, University of Barcelona, Spain.
authors.forename: R
authors.initials: R
authors.lastname: Sanmartí
authors.forename: A
authors.initials: A
authors.lastname: Collado
authors.forename: J
authors.initials: J
authors.lastname: Gratacós
authors.forename: B E
authors.initials: BE
authors.lastname: Herrera
authors.forename: J
authors.initials: J
authors.lastname: Font
authors.forename: J D
authors.initials: JD
authors.lastname: Cañete
authors.forename: C
authors.initials: C
authors.lastname: Orellana
authors.forename: J
authors.initials: J
authors.lastname: Muñoz-Gomez
mesh_terms: D000328:Adult; D000368:Aged; D001799:Blood Sedimentation; D003402:Creatine Kinase / Q000097:blood*; D005260:Female; D006801:Humans; D007249:Inflammation / Q000097:blood / Q000188:drug therapy; D008297:Male; D008875:Middle Aged; D012216:Rheumatic Diseases / Q000097:blood* / Q000188:drug therapy; D013256:Steroids / Q000627:therapeutic use
chemical_list: D013256:Steroids; D003402:Creatine Kinase