Serum alkaline phosphatase during hormone treatment in early postmenopausal women. A model for establishing optimal prophylaxis and treatment in postmenopausal osteoporosis.

We propose a new model for use in establishing optimal treatment of postmenopausal osteoporosis. When hydroxyproline is taken as an estimate of bone resorption and alkaline phosphatase (ALP) of bone formation, the model indicates that the difference between hydroxyproline and ALP is reflected in the negative calcium balance, and thus the decline in bone mineral content (BMC). Since BMC increases during oestrogen treatment in postmenopausal women, in whom ALP declines gradually, it is postulated that this only happens because of a rapid decline in hydroxyproline. This decline together with BMC, must be dose-related since changes in ALP are uncorrelated to the oestrogen dose. This model fits the generally accepted opinion that the effect of oestrogen on bone loss in postmenopausal osteoporosis is limited, declines with age, and is dose-related. The model indicates that oestrogen treatment should be introduced early after the menopause in order to obtain the optimum prophylactic effect.