Vitamin D insufficiency is prevalent and vitamin D is inversely associated with parathyroid hormone and calcitriol in pregnant adolescents

Bridget E. Young, Thomas J. McNanley, Elizabeth M. Cooper, Allison W. McIntyre, Frank Witter, Z. Leah Harris, Kimberly O. O'Brien

Research output: Contribution to journalArticle

Abstract

Few large studies have assessed changes in calcitropic hormones and maternal 25-hydroxyvitamin D (25(OH)D) status across pregnancy, and how this may impact maternal bone turnover and neonatal hormone status. We aimed to identify determinants of 25(OH)D, parathyroid hormone (PTH), and calcitriol across pregnancy in a longitudinal study of 168 pregnant adolescents (≤18 years of age). Maternal 25(OH)D, PTH, and calcitriol were assessed at mid-gestation (∼26 weeks), delivery, and in cord blood. Data were related to measures of maternal anthropometrics, dietary intake, physical activity, and bone turnover markers. Approximately 50% of teens and their infants had serum 25(OH)D a;circ 20 ng/mL; 25(OH)D was lower in African Americans versus whites (p < 0.001). PTH increased across gestation (p < 0.001). Elevated PTH (≥60 pg/mL) was detected in 25% of adolescents at delivery, and was associated with increased concentrations of serum N-telopeptide (NTX) (p=0.028). PTH and calcitriol did not significantly differ across the range of Ca intake consumed (257-3220 mg/d). In the group as a whole, PTH was inversely associated with 25(OH)D in maternal circulation at mid-gestation (p=0.023) and at delivery (p=0.019). However, when the cohort was partitioned by 25(OH)D status, this relationship was only present in those with 25(OH)D≤20 ng/mL, suggestive of a threshold below which 25(OH)D impacts PTH during pregnancy. Mid-gestation 25(OH)D was inversely associated with calcitriol at delivery (p=0.023), irrespective of Ca intake. Neonatal PTH and calcitriol were significantly lower than (p=0.001), but unrelated to maternal concentrations. These findings indicate that maternal 25(OH)D status plays a role in calcitropic hormone regulation in pregnant adolescents.

Original languageEnglish (US)
Pages (from-to)177-186
Number of pages10
JournalJournal of Bone and Mineral Research
Volume27
Issue number1
DOIs
StatePublished - Jan 1 2012

Keywords

  • 1,25-dihydroxyvitamin D
  • 25-hydroxyvitamin D
  • Adolescence
  • Parathyroid hormone
  • Pregnancy

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Orthopedics and Sports Medicine

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