Determinants of forearm bone density in premenopausal women: a study in one general practice.

Predictors of distal and proximal forearm bone density, measured by photon absorbtiometry, were investigated in 248 premenopausal women aged 39-56 years. Only one strong predictor of lower bone density was found--history of previous fracture at any site (P less than 0.001). Two other factors showed a weaker association with density, but only at the distal site--history of diuretic use showed a positive association (P less than 0.02) whereas alkaline phosphatase level was inversely correlated with density (P less than 0.01). Other factors were not significant predictors: these included age, calcium intake, level of exercise, anthropometric measures of obesity, serum calcium level, parity, lactation history, a menopausal symptom history, use of the contraceptive pill, smoking and alcohol intake. These results contrast with the far stronger predictors found for postmenopausal women and suggest that genetic endowment rather than lifestyle may be the major determinant of bone density before the menopause.