Hormonal factors in osteoporosis.

Primary osteoporosis is a ubiquitous disease of unknown etiology. The condition undoubtedly has multiple causes and the metabolic pattern of bone loss may vary significantly from case to case. Five hormones, PTH, gonadal steroids, CT, T3 and T4, and glucocorticoids, and possibly a sixth, GH, have fundamental actions on bone metabolism and may therefore be causally involved in primary osteoporosis. A consideration of selected data on hormonal interactions culled from a much larger body of experimental and clinical data leads to the conclusion that in vitro studies, animal research, and data obtained in postmenopausal women with age-related bone atrophy, but not osteoporosis, have yielded considerable data relating to bone metabolism, but have failed to define the causes or treatment of primary osteoporosis. There has been excessive emphasis on hormonal reactions relating to bone metabolism and bone cell function, and too little concern for nonhormonal factors which might influence the kinetics of skeletal turnover through alterations in bone cell activity. A practical approach to the cause(s) and treatment in the only suitable model, the human with osteoporosis, is proposed with the expectation that a better insight into the pathogenesis of the condition will be achieved.