title: Low serum levels of vitamin D in idiopathic inflammatory myopathies.
abstract: OBJECTIVE
  To evaluate serum levels of 25(OH) vitamin D in patients with idiopathic inflammatory myopathies (IIM) (polymyositis (PM), dermatomyosistis (DM), inclusion body myositis (IBM) and juvenile DM (JDM)) and to compare these with healthy controls.
  
  
  METHODS
  Serum samples from 149 patients with IIM and 290 healthy controls matched for gender and the month of blood sampling were analysed for 25(OH) vitamin D. ORs for vitamin D classes with 95% CI were calculated using a matched (conditional) logistic regression model. Groups were compared by the Kruskal-Wallis test and p values <0.05 were considered significant.
  
  
  RESULTS
  Patients with IIM had significantly lower serum levels of 25(OH) vitamin D than healthy controls (median 39 (10-168) nmol/l vs 68 (19-197) nmol/l; p=0.0001). There was no significant difference in vitamin D levels between the myositis subgroups. When vitamin D levels were subclassified into deficient (<50 nmol/l), insufficient (50-74 nmol/l) and normal (≥75 nmol/l), most of the patients with PM (68%), DM (65%) and IBM (53%) had deficient levels compared with only 60 (21%) healthy individuals. In patients with IIM the OR for deficient versus normal was 17.7 (95% CI 8.1 to 38.6) and the OR for insufficient versus normal was 2.4 (95% CI 1.2 to 4.7).
  
  
  CONCLUSIONS
  Low serum levels of vitamin D were found in most patients with IIM and may confer a risk factor for developing adult myositis, similar to some other autoimmune diseases.
authors.affiliation: Rheumatology Unit, Danderyd's Hospital, Karolinska Institutet, Stockholm 18288, Sweden. payam.azali@ds.se
authors.forename: Payam
authors.initials: P
authors.lastname: Azali
authors.forename: Sevim
authors.initials: S
authors.lastname: Barbasso Helmers
authors.forename: Ingrid
authors.initials: I
authors.lastname: Kockum
authors.forename: Tomas
authors.initials: T
authors.lastname: Olsson
authors.forename: Lars
authors.initials: L
authors.lastname: Alfredsson
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Charles
authors.forename: Karin
authors.initials: K
authors.lastname: Piehl Aulin
authors.forename: Ingrid E
authors.initials: IE
authors.lastname: Lundberg
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D003430:Cross-Sectional Studies; D003882:Dermatomyositis / Q000097:blood / Q000453:epidemiology; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009220:Myositis / Q000097:blood / Q000453:epidemiology*; D018979:Myositis, Inclusion Body / Q000097:blood / Q000453:epidemiology; D017285:Polymyositis / Q000097:blood / Q000453:epidemiology; D012189:Retrospective Studies; D012307:Risk Factors; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000453:epidemiology*; D055815:Young Adult
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D