RESUMO
The influences of heredity and environmental factors on radial bone mass were evaluated in 84 premenopausal mothers with their biological daughters (ages 18-22). Mid- and distal radial bone mineral content (BMC) and density (BMD) were assessed using single-photon absorptiometry. As a group, the daughters (mean age 18.6 years) had 5-10% less bone mass at both the distal and midradial sites than their mothers (mean age 44.2 years). Familial resemblance estimates showed significant relationships between mothers and daughters for mid- and distal BMC and BMD after considering the influence of body mass index (BMI). Daughters with a maternal family history of osteoporosis had 6-7% lower but nonsignificant values of mid- (P = 0.086) and distal BMC (P = 0.075) compared to values of women with a negative family history, whereas mothers with a positive family history had 3-4% lower (NS) values of distal and mid-BMC compared to those of mothers with a negative family history after adjustment for BMI. Multiple regression analyses showed BMI to be the most important determinant of the bone values of the mothers, and both BMI and dietary calcium intake were found to be significant for the daughters. The findings of this study suggest that hereditary contributions from the mothers play an overwhelmingly critical role in the accrual of bone mass by their daughters by ages 18-22, but that environmental influences on bone consolidation during the premenopausal decades may be more important in promoting optimal (peak) bone mass and thereby may help to delay the postmenopausal onset of osteoporotic fractures.
