title: Relationship between disease activity and serum levels of vitamin D and parathyroid hormone in rheumatoid arthritis.
abstract: OBJECTIVE
  Measuring vitamin D and its regulating hormones in the serum might be an accurate method for assessment of rheumatoid arthritis (RA) activity. We tested the hypothesis that the serum levels of vitamin D and parathyroid hormone (PTH) are associated with the grade of disease activity in an unselected cohort of patients with RA.
  
  
  METHODS
  A total of 158 patients who met the American College of Rheumatology criteria for RA were examined and categorized as the patients with the active RA (n = 87) and silent RA (n = 71). Blood samples were obtained after at least eight-hour overnight fasting and the levels of 25-OH-vitamin D and PTH were measured.
  
  
  RESULTS
  The levels of the vitamin D in patients with active RA were significantly lower than in those with silent RA (49.38±38.21 versus 64.64±43.61 nmol/l; p = 0.022). The PTH serum level lower than the normal range (< 0.8 nmol/l) was statistically observed similar in the active RA group compared with another ones (10.3 % versus 4.2 %, p = 0.149). Serum levels of vitamin D and PTH were not influenced by patients' gender and age as well as the duration of disease.
  
  
  CONCLUSIONS
  Serum level of vitamin D was inversely related to RA activity and this relationship might be independent of PTH secretion or activity.
authors.affiliation: Semnan University of Medical Sciences, Semnan, Iran. moghimi_jam@yahoo.com
authors.forename: J
authors.initials: J
authors.lastname: Moghimi
authors.forename: A
authors.initials: A
authors.lastname: Sadeghi
authors.forename: M
authors.initials: M
authors.lastname: Malek
authors.forename: R
authors.initials: R
authors.lastname: Ghorbani
mesh_terms: D000328:Adult; D001172:Arthritis, Rheumatoid / Q000175:diagnosis* / Q000378:metabolism*; D015415:Biomarkers / Q000097:blood; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood*; D012720:Severity of Illness Index; D013472:Sunlight; D014807:Vitamin D / Q000096:biosynthesis / Q000097:blood*
chemical_list: D015415:Biomarkers; D010281:Parathyroid Hormone; D014807:Vitamin D