title: Vitamin D, secondary hyperparathyroidism, and preeclampsia.
abstract: BACKGROUND
  Secondary hyperparathyroidism, which is defined by a high concentration of intact parathyroid hormone when circulating 25-hydroxyvitamin D [25(OH)D] is low, is a functional indicator of vitamin D insufficiency and a sign of impaired calcium metabolism. Two large randomized controlled trials examined effects of calcium supplementation on preeclampsia but did not consider the vitamin D status of mothers.
  
  
  OBJECTIVE
  We examined the association of secondary hyperparathyroidism with risk of preeclampsia.
  
  
  METHODS
  Circulating maternal 25-hydroxyvitamin D [25(OH)D] and intact parathyroid hormone were measured at entry to care (mean ± SD: 13.7 ± 5.7 wk) using prospective data from a cohort of 1141 low-income and minority gravidae.
  
  
  RESULTS
  Secondary hyperparathyroidism occurred in 6.3% of the cohort and 18.4% of women whose 25(OH)D concentrations were <20 ng/mL. Risk of preeclampsia was increased 2.86-fold (95% CI: 1.28-, 6.41-fold) early in gestation in these women. Gravidae with 25(OH)D concentrations <20 ng/mL who did not also have high parathyroid hormone and women with high parathyroid hormone whose 25(OH)D concentrations were >20 ng/mL were not at increased risk. Intact parathyroid hormone was related to higher systolic and diastolic blood pressures and arterial pressure at week 20 before clinical recognition of preeclampsia. Energy-adjusted intakes of total calcium and lactose and circulating 25(OH)D were correlated inversely with systolic blood pressure or arterial pressure and with parathyroid hormone.
  
  
  CONCLUSIONS
  Some women who are vitamin D insufficient develop secondary hyperparathyroidism, which is associated with increased risk of preeclampsia.
authors.affiliation: Department of Obstetrics and Gynecology, University of Medicine and Dentistry of New Jersey, Stratford, NJ, USA. schollto@rowan.edu
authors.forename: Theresa O
authors.initials: TO
authors.lastname: Scholl
authors.forename: Xinhua
authors.initials: X
authors.lastname: Chen
authors.forename: T Peter
authors.initials: TP
authors.lastname: Stein
mesh_terms: D000293:Adolescent; D000328:Adult; D001794:Blood Pressure; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology; D002136:Calcium, Dietary / Q000378:metabolism / Q000494:pharmacology*; D002149:Energy Intake; D005260:Female; D006801:Humans; D006962:Hyperparathyroidism, Secondary / Q000097:blood / Q000453:epidemiology / Q000209:etiology*; D007785:Lactose / Q000494:pharmacology; D010281:Parathyroid Hormone / Q000097:blood*; D011225:Pre-Eclampsia / Q000097:blood / Q000209:etiology*; D011247:Pregnancy; D015995:Prevalence; D012307:Risk Factors; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000150:complications*; D055815:Young Adult
chemical_list: D002136:Calcium, Dietary; D010281:Parathyroid Hormone; D014807:Vitamin D; C104450:25-hydroxyvitamin D; D007785:Lactose; D002118:Calcium