Relationships among vitamin D levels, parathyroid hormone, and calcium absorption in young adolescents

J Clin Endocrinol Metab. 2005 Oct;90(10):5576-81. doi: 10.1210/jc.2005-1021. Epub 2005 Aug 2.


Background: Evidence suggests that vitamin D status in adults, as assessed by serum 25-hydroxyvitamin D (25-OHD), is positively associated with calcium absorption fraction and inversely associated with serum PTH. Few comparable pediatric data exist.

Objectives: The objective of this study was to evaluate the relationships among vitamin D status, PTH, and calcium absorption in midpubertal boys and girls.

Methods: Calcium absorption was measured as part of an evaluation of the effects of prebiotics (inulin-type fructans) using a stable isotope method in 93 young adolescents, 12.7 +/- 1.0 yr of age, receiving diets averaging approximately 900 mg/d calcium.

Results: A significant positive relation to calcium absorption was found for serum 1,25-dihydroxyvitamin D (P = 0.048) and PTH (P = 0.007), but not for 25-OHD (P = 0.77). PTH was significantly inversely related to 25-OHD and was positively related to serum 1,25-dihydroxyvitamin D and osteocalcin. PTH was marginally significantly inversely related to lumbar spinal, but not whole body, bone mineral density.

Conclusions: These data suggest that in adolescents, especially in the presence of vitamin D insufficiency, PTH secretion increases to adapt to higher rates of bone formation associated with growth. This results in higher serum 1,25(OH)2D concentrations and increased calcium absorption results. Vitamin D status, as reflected by the serum 25-OHD level, is not closely related to calcium absorption. Whether adaptation to low serum 25-OHD is adequate under physiologically stressful situations, including those leading to very low serum 25-OHD levels, is unknown.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • 25-Hydroxyvitamin D 2 / metabolism
  • Adolescent
  • Bone Density
  • Calcium / metabolism*
  • Child
  • Diet
  • Dietary Supplements
  • Endpoint Determination
  • Female
  • Genotype
  • Humans
  • Male
  • Osteocalcin / blood
  • Parathyroid Hormone / blood*
  • Puberty / physiology
  • Vitamin D / blood*


  • Parathyroid Hormone
  • Osteocalcin
  • Vitamin D
  • 25-Hydroxyvitamin D 2
  • Calcium