title: Primary hyperparathyroidism and celiac disease: a population-based cohort study.
abstract: BACKGROUND
  Celiac disease (CD) has been linked to several endocrine disorders, including type 1 diabetes and thyroid disorders, but little is known regarding its association to primary hyperparathyroidism (PHPT).
  
  
  OBJECTIVE
  The aim of the study was to examine the risk of PHPT in patients with CD.
  
  
  METHODS
  We conducted a two-group exposure-matched nonconcurrent cohort study in Sweden. A Cox regression model estimated hazard ratios (HR) for PHPT.
  
  
  METHODS
  We identified 17,121 adult patients with CD who were diagnosed through biopsy reports (Marsh 3, villous atrophy) from all 28 pathology departments in Sweden. Biopsies were performed in 1969-2008, and biopsy report data were collected in 2006-2008. Statistics Sweden then identified 85,166 reference individuals matched with the CD patients for age, sex, calendar period, and county.
  
  
  METHODS
  PHPT was measured according to the Swedish national registers on inpatient care, outpatient care, day surgery, and cancer.
  
  
  RESULTS
  During follow-up, 68 patients with CD and 172 reference individuals developed PHPT (HR=1.91; 95% confidence interval=1.44-2.52). The absolute risk of PHPT was 42/100,000 person-years with an excess risk of 20/100,000 person-years. The risk increase for PHPT only occurred in the first 5 yr of follow-up; after that, HR were close to 1 (HR=1.07; 95% confidence interval=0.70-1.66).
  
  
  CONCLUSIONS
  CD patients are at increased risk of PHPT, but the absolute risk is small, and the excess risk disappeared after more than 5 yr of follow-up.
authors.affiliation: Department of Pediatrics, Örebro University Hospital, 701 85 Örebro, Sweden. jonasludvigsson@yahoo.com
authors.forename: Jonas F
authors.initials: JF
authors.lastname: Ludvigsson
authors.forename: Olle
authors.initials: O
authors.lastname: Kämpe
authors.forename: Benjamin
authors.initials: B
authors.lastname: Lebwohl
authors.forename: Peter H R
authors.initials: PH
authors.lastname: Green
authors.forename: Shonni J
authors.initials: SJ
authors.lastname: Silverberg
authors.forename: Anders
authors.initials: A
authors.lastname: Ekbom
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002446:Celiac Disease / Q000175:diagnosis / Q000453:epidemiology*; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D049950:Hyperparathyroidism, Primary / Q000453:epidemiology*; D015994:Incidence; D008297:Male; D008875:Middle Aged; D012042:Registries; D012306:Risk; D012307:Risk Factors; D013548:Sweden