title: Changes in vitamin D and parathyroid hormone metabolism in incident pediatric Crohn's disease.
abstract: BACKGROUND
  Prior studies of vitamin D metabolism in Crohn's disease (CD) did not include controls or examine changes following diagnosis. This study examined associations among 25-hydroxyvitamin D [25(OH)D], 1,25-dihydroxyvitamin D [1,25(OH)(2)D], and parathyroid hormone (PTH) levels in incident pediatric CD, compared with controls, and following diagnosis.
  
  
  METHODS
  Serum vitamin D and PTH were measured at diagnosis (n = 78), 6, 12, and a median of 43 months (n = 52) later in CD participants, and once in 221 controls. Multivariate regression was used to examine baseline associations and quasi-least squares regression to assess subsequent changes.
  
  
  RESULTS
  At diagnosis, 42% of CD participants were 25(OH)D-deficient (<20 ng/mL). The odds ratio for deficiency was 2.1 (95% confidence interval [CI]: 1.1, 3.9; P < 0.05) vs. controls, adjusted for age, race, and season. 1,25(OH)(2)D was lower in CD vs. controls (P < 0.05), adjusted for 25(OH)D, tumor necrosis factor alpha (TNF-α), and PTH. TNF-α was associated with lower 1,25(OH)(2)D (P < 0.05), and the positive association between PTH and 1,25(OH)(2)D in controls was absent in CD (interaction P = 0.02). Among participants with 25(OH)D <30 ng/mL, CD was associated with lower PTH (P < 0.05) vs. controls. Following diagnosis, 25(OH)D and 1,25(OH)(2)D improved (P < 0.001). At the final visit, 3% were 25(OH)D-deficient, PTH was no longer low relative to 25(OH)D, and 1,25(OH)(2)D was significantly elevated (P < 0.001) compared with controls.
  
  
  CONCLUSIONS
  Incident CD was associated with 25(OH)D and 1,25(OH)2D deficiency and a relative hypoparathyroidism that resolved following diagnosis. Inflammatory cytokine suppression of PTH and renal 1-α-hyroxylase may contribute to these alterations.
authors.affiliation: Department of Pediatrics, Yale-New Haven Children's Hospital, New Haven, Connecticut, USA.
authors.forename: Aaron R
authors.initials: AR
authors.lastname: Prosnitz
authors.forename: Mary B
authors.initials: MB
authors.lastname: Leonard
authors.forename: Justine
authors.initials: J
authors.lastname: Shults
authors.forename: Babette S
authors.initials: BS
authors.lastname: Zemel
authors.forename: Bruce W
authors.initials: BW
authors.lastname: Hollis
authors.forename: Lee A
authors.initials: LA
authors.lastname: Denson
authors.forename: Robert N
authors.initials: RN
authors.lastname: Baldassano
authors.forename: Aaron B
authors.initials: AB
authors.lastname: Cohen
authors.forename: Meena
authors.initials: M
authors.lastname: Thayu
mesh_terms: D000293:Adolescent; D000328:Adult; D001823:Body Composition; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D003424:Crohn Disease / Q000453:epidemiology / Q000378:metabolism*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D010281:Parathyroid Hormone / Q000097:blood*; D011379:Prognosis; D013022:South Carolina / Q000453:epidemiology; D014409:Tumor Necrosis Factor-alpha / Q000097:blood*; D014807:Vitamin D / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000097:blood*; D014808:Vitamin D Deficiency / Q000097:blood* / Q000209:etiology; D055815:Young Adult
chemical_list: D010281:Parathyroid Hormone; D014409:Tumor Necrosis Factor-alpha; D014807:Vitamin D; C097949:1,25-dihydroxyvitamin D; C104450:25-hydroxyvitamin D