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ARS Home » Plains Area » Houston, Texas » Children's Nutrition Research Center » Research » Publications at this Location » Publication #203176
Title: Relationships among vitamin D levels, parathyroid hormone, and calcium absorption in young adolescents

Author
item Abrams, Steven
item Griffin, Ian
item HAWTHORNE, KELI - BAYLOR COLLEGE OF MEDICIN
item GUNN, SHEILA - BAYLOR COLLEGE OF MEDICIN
item GUNDBERG, CAREN - YALE UNIV SCHOOL OF MEDIC
item CARPENTER, THOMAS - YALE UNIV SCHOOL OF MEDIC

Submitted to: Journal of Clinical Endocrinology and Metabolism
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/20/2005
Publication Date: 10/1/2005
Citation: Abrams, S.A., Griffin, I.J, Hawthorne, K.M., Gunn, S.K., Gundberg, C.M., Carpenter, T.O. 2005. Relationships among vitamin D levels, parathyroid hormone, and calcium absorption in young adolescents. Journal of Clinical Endocrinology and Metabolism. 90(10):5077-5081.

Interpretive Summary: Research suggests that many Americans are low in vitamin D in their diet. But there are few data about this in teenagers and almost no information about how vitamin D affects calcium absorption in teenagers. We studied the levels of vitamin D in the blood of teenagers and how it affected calcium absorption and hormone levels. We found that although slightly low vitamin D levels were common and led to effects on other hormones, there did not appear to be any effect of these levels on calcium absorption. This result is different than in adults. More studies are needed to determine how much is the ideal amount of vitamin D in the diet or what the best vitamin D levels are in the blood.

Technical Abstract: 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.