title: Glutathione reductase activity, riboflavin status, and disease activity in rheumatoid arthritis.
abstract: OBJECTIVE
  To measure erythrocyte glutathione reductase (EGR) activity and riboflavin status, and their relations to disease activity, in rheumatoid arthritis patients compared to healthy controls.
  
  
  METHODS
  Patients with rheumatoid arthritis were classified as active if there were features of articular inflammation which required initiation or change of disease modifying therapy, and as inactive if they had little evidence of articular inflammation. EGR was measured in patients and healthy controls by a functional assay with or without the addition of flavin adenine dinucleotide (FAD). The ratio of stimulated EGR (with FAD added) to basal EGR (no added FAD), which measures riboflavin status, is known as the EGR activation coefficient (EGRAC). An EGRAC > or = 1.3 represents biochemical riboflavin deficiency.
  
  
  RESULTS
  91 patients with rheumatoid arthritis, including 57 with active disease, and 220 healthy controls were studied. Both basal and stimulated EGR were significantly higher in patients with rheumatoid arthritis (P = 0.0001) than in controls. Biochemical riboflavin deficiency was identified in 41% controls and 33% patients with active rheumatoid arthritis but was significantly less frequent (9%) in patients with inactive compared to active disease (P = 0.02) or healthy controls (P = 0.0006). Pain score, articular index, C reactive protein, and erythrocyte sedimentation rate were increased in patients with riboflavin deficiency (all P < 0.02).
  
  
  CONCLUSIONS
  Higher basal and stimulated EGR might be expected in patients with rheumatoid arthritis in response to chronic oxidative stress due to synovial inflammation. The association of riboflavin deficiency with increased disease activity suggests that impaired EGR activity could facilitate continuing inflammation in these patients.
authors.affiliation: Department of Rheumatology, City Hospital NHS Trust, Birmingham, United Kingdom.
authors.forename: D M
authors.initials: DM
authors.lastname: Mulherin
authors.forename: D I
authors.initials: DI
authors.lastname: Thurnham
authors.forename: R D
authors.initials: RD
authors.lastname: Situnayake
mesh_terms: D000328:Adult; D001172:Arthritis, Rheumatoid / Q000378:metabolism* / Q000503:physiopathology; D004789:Enzyme Activation; D005260:Female; D005182:Flavin-Adenine Dinucleotide / Q000378:metabolism; D005980:Glutathione Reductase / Q000097:blood / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement; D012257:Riboflavin Deficiency / Q000201:enzymology; D012720:Severity of Illness Index
chemical_list: D005182:Flavin-Adenine Dinucleotide; D005980:Glutathione Reductase