Interrelationship between bone turnover markers and dietary calcium intake in pregnant women: A longitudinal study

This longitudinal study evaluated bone turnover and the interrelationship between changes in bone biomarkers and habitual dietary calcium intake during pregnancy in a group of women ranging widely with regard to dietary calcium intake. Thirty-nine healthy pregnant and 30 nonpregnant women were studied. Calcium, phosphorus, 1α,25-dihydroxyvitamin D (1,25diHOD), bone alkaline phosphatase (bALP), carboxyterminal propeptides of type I procollagen (PICP) and carboxyterminal telopeptides of type I collagen (βCTX and ICTP) were measured in serum and calcium, and creatinine and aminoterminal telopeptide (NTX) were determined in urine. Serum calcium and phosphorus did not change but the urinary Ca/Creat ratio and 1,25diHOD increased throughout pregnancy (P NTX >ICTP. Serum 1,25 diHOD versus calcium intake showed a positive and significant correlation (r = 0.51, P < 0.02). A negative correlation between the absolute change in βCTX, NTX, and b-ALP between the third and second trimester and calcium intake at the end of pregnancy was observed in pregnant women who did not cover adequately calcium intake requirements (r = -0.47, P < 0.03; r = -0.41, P < 0.05; and r = -0.43, P < 0.05, respectively). These results suggest that skeletal response to pregnancy may not be entirely independent of maternal calcium intake, especially in women with usually low calcium intake. In summary, not only hormonal changes in calcium metabolism that occur during pregnancy but also other considerations, such as low dietary calcium intake, may lead to an increment in the biological activity of the skeleton. Additional studies must be conducted to confirm our findings and to gain a better understanding of skeletal response to a low calcium intake during pregnancy.Fil: Zeni, Susana Noemi. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín. División Osteopatías; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Inmunología, Genética y Metabolismo. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Inmunología, Genética y Metabolismo; ArgentinaFil: Soler, Carlos R. Ortela. Hospital Interzonal General de Agudos Paroissien (higa Paroissien) ; Gobierno de la Provincia de Buenos Aires;Fil: Lazzari, Araceli. Hospital Interzonal General de Agudos Paroissien (higa Paroissien) ; Gobierno de la Provincia de Buenos Aires;Fil: Lopez, Laura Beatriz. Hospital Interzonal General de Agudos Paroissien (higa Paroissien) ; Gobierno de la Provincia de Buenos Aires;Fil: Suarez, Marisa. Hospital Interzonal General de Agudos Paroissien (higa Paroissien) ; Gobierno de la Provincia de Buenos Aires;Fil: Di Gregorio, Silvana. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín. División Osteopatías; ArgentinaFil: Somoza, Julia Isabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Inmunología, Genética y Metabolismo. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Inmunología, Genética y Metabolismo; Argentina. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín. División Osteopatías; ArgentinaFil: Pita Martín de Portela, María Luz. Universidad de Buenos Aires. Facultad de Farmacia y Bioquimica. Departamento de Sanidad Nutricion Bromatologia y Toxicologia. Catedra de Nutricion.; Argentin