Perinatal parathyroid hormone, vitamin D metabolites, and calcitonin in man.
Plasma levels of calcium and of parathyroid hormone (PTH) were comparable in the mothers at delivery and in nonpregnant controls; magnesium was decreased (P < 0.001) in maternal blood; and phosphate (P < 0.001), 1,25-dihydroxyvitamin D (1,25(OH)2D) (P < 0.001), and calcitonin (CT) (P < 0.01) were raised. Cord levels of calcium (P < 0.01), magnesium (P < 0.05), and CT (P < 0.01) were higher, and PTH (P < 0.01) was lower than in the maternal blood. Levels of 25(OH)D, 1,25(OH)2D, and 24,25(OH)2D lower in fetal than in maternal blood (P < 0.01) and significant linear correlations between the vitamin D metabolites examined in mothers and neonates (P < 0.001) are consistent with a diffusion barrier across the placenta and/or different affinities of binding proteins. Plasma levels of 25(OH)D and 24,25(OH)2D were significantly related (P < 0.01), suggesting precursor product type, relationships. Levels of 1,25(OH)2D higher in arterial than in venous umbilical blood (P = 0.06, sign test; P < 0.005, paired t test) suggest that the fetus participates in the synthesis of 1,25(OH)2D. Maternal PTH was significantly related to the arteriovenous difference of 1,25(OH)2D levels (P < 0.01) in cord blood, and it possibly enhances the synthesis of 1,25(OH)2D during the final stage of fetal development.
D000293:Adolescent; D000328:Adult; D002116:Calcitonin / Q000378:metabolism*; D002118:Calcium / Q000097:blood*; D005260:Female; D005312:Fetal Blood / Q000378:metabolism; D006801:Humans; D006887:Hydroxycholecalciferols / Q000378:metabolism*; D007231:Infant, Newborn; D008274:Magnesium / Q000097:blood; D010281:Parathyroid Hormone / Q000378:metabolism*; D010500:Perinatology; D010710:Phosphates / Q000378:metabolism; D011247:Pregnancy
D006887:Hydroxycholecalciferols; D010281:Parathyroid Hormone; D010710:Phosphates; D002116:Calcitonin; D008274:Magnesium; D002118:Calcium