title: Pregnancy and lactation affect markers of calcium and bone metabolism differently in adolescent and adult women with low calcium intakes.
abstract: Physiologic adaptation to the high calcium demand during pregnancy and lactation may be different in adolescents than in adults, particularly at low calcium intake. The aim of this cross-sectional study was to compare biochemical markers of calcium and bone metabolism between adolescent (14-19 y) and adult (21-35 y) women with calcium intake approximately 500 mg/d, in three different physiologic states, i.e., control (nonpregnant, nonlactating; NPNL), pregnant and lactating. Markers of calcium metabolism [serum Ca, P and intact parathyroid hormone (iPTH); urinary Ca and P] and of bone turnover [urinary deoxypyridinoline (D-Pyr) and plasma bone alkaline phosphatase (BAP)] were measured in NPNL (adolescents, n = 12 and adults, n = 25), pregnant (adolescents, n = 30 and adults, n = 36) and lactating (adolescents, n = 19 and adults, n = 26) women. In the NPNL women, iPTH, D-Pyr and BAP were higher (P < 0.001) and urinary Ca was lower (P < 0.001) in adolescents than in adults. Serum iPTH was higher (P < 0.001) and urinary Ca was lower (P < 0.01) in adolescents than in adults also in pregnancy and lactation. Compared with NPNL women, serum Ca decreased (P < 0.001) with pregnancy in adolescents but not in adults. The increase in D-Pyr with pregnancy and lactation was very pronounced in adults ( approximately 130%, P < 0.001) but less in adolescents (<25%, P < 0.01). BAP increased (P < 0.001) with pregnancy and lactation in adults ( approximately 60%) but decreased (P < 0.001) with pregnancy in adolescents ( approximately 13%). Pregnancy and lactation appear to affect bone turnover in adolescent and adult women with low calcium intake differently.
authors.affiliation: Laboratório de Bioquímica Nutricional e de Alimentos, Departamento de Bioquímica, Instituto de Química, Universidade Federal do Rio de Janeiro, Brazil.
authors.forename: Flávia F
authors.initials: FF
authors.lastname: Bezerra
authors.forename: Fabrícia P
authors.initials: FP
authors.lastname: Laboissière
authors.forename: Janet C
authors.initials: JC
authors.lastname: King
authors.forename: Carmen M
authors.initials: CM
authors.lastname: Donangelo
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D001842:Bone and Bones / Q000187:drug effects / Q000378:metabolism*; D002118:Calcium / Q000097:blood / Q000378:metabolism*; D002136:Calcium, Dietary / Q000494:pharmacology*; D005260:Female; D006801:Humans; D007774:Lactation / Q000502:physiology*; D010281:Parathyroid Hormone / Q000097:blood; D011247:Pregnancy / Q000502:physiology*; D012016:Reference Values; D012709:Serum Albumin / Q000378:metabolism
chemical_list: D002136:Calcium, Dietary; D010281:Parathyroid Hormone; D012709:Serum Albumin; D002118:Calcium