Bone mineral, serum calcium, and dietary intakes of mother/daughter pairs.

Data on factors potentially responsible for familial differences in the incidence of postmenopausal osteoporosis were obtained for 26 mother/daughter pairs. The factors were: bone mineral content of the radius (BMC); bone mineral content to bone width ratio (BMC/W); serum ionized (Ca++), ultrafiltrable (UF-Ca) and total calcium (T-Ca), ultrafiltrable and total magnesium, and 25-hydroxyvitamin D; and 7-day dietary intakes of selected nutrients. The BMC, BMC/W, and serum calcium fractions of the mothers were significantly correlated with those of the daughters. Although the BMC of the mothers was related to their caloric intakes, the interrelations between BMC and other variables of each group were not significant. Estimates of heritability, a measure of familial resemblance, were 0.724 for BMC; 0.570 for BMC/W; and 0.932, 0.916, and 0.668 for Ca++, UF-Ca, and T-Ca, respectively. Mothers with low BMC tended to have daughters with low BMC; there were also familial resemblances in serum calcium fractions.