Role of hormonal factors in the pathogenesis of postmenopausal osteoporosis.

In 47 women with postmenopausal osteoporosis, pretreatment studies by microradiography, radioimmunoassay and other methods showed increased bone resorption, normal bone formation, and decreased serum immunoreactive parathyroid hormone (PTH). In patients treated with a physiologic replacement dose of estrogen, bone resorption decreased to normal and PTH increased after short-term therapy; bone formation decreased to very low levels after long-term therapy. These data indicate that, in most patients, both an intrinsic abnormality of bone cell function and a disruption of the normal regulation of bone turnover by PTH and sex hormones, as a result of the menopause, are important in the pathogenesis of osteoporosis.