The effects of sex steroid and corticosteroid hormones on bone

Abstract

Age-related bone loss (simple osteoporosis) in women is associated with a rise in bone resorption and with no change in forming surfaces. This rise in bone resorption is presumably due to oestrogen deficiency and can be reversed by oestrogens. Simple osteoporosis in men is due to a decline in bone formation with no rise in bone resorption. It is suggested that this decline in bone formation may reflect a decline in the androgen levels with age. In both sexes, accelerated osteoporosis is associated with greatly increased bone resorption probably secondary to malabsorption of calcium. However, in women with primary accelerated osteoporosis some reduction in bone formation is also pressent and is associated with reduced skinfold thickness. This may represent an androgen deficiency. Oestrogen therapy improves calcium balance by lowering bone resorption and norethisterone has much the same effect. Testosterone seems to act in a rather similar way—the anticipated effect on bone formation is small. Other anabolic compounds which have been tested also have only a small effect on bone formation. The effect of corticosteroids on calcium metabolism is mainly manifest in reduced calcium absorption which produces increased bone resorption. The depression of bone formation by corticosteroids may contribute to corticosteroid osteoporosis but does not seem to be the main determinant.