Changes in Serum Calcium and Phosphorus during Stilboestrol Treatment of Osteoporosis.

The value of oestrogens in the treatment of osteoporosis has been shown by two main types of evidence. Firstly, increased calcium retention, due to a reduction in both faecal and urinary excretion, has been shown by metabolic balance studies (Reifenstein and Albright 1947). Secondly, the progress of the disease, as judged by height loss and bone density, is arrested (Henneman and Wallach 1957), and furthermore the loss of height which normally occurs in post-menopausal women can be prevented by oestrogens (Hernberg I 960). However, oestrogens have never been shown to increase bone density and their mode ofaction is uncertain. Oestrogens have been shown to stimulate osteogenesis in many different species, and to reverse in this way the osteoporosis which follows orchidectomy and adrenalectomy in rats (Caldwell 1962). Most workers have assumed that this action also occurs in man, and that the reduction in calcium excretion is secondary to a direct action on bone. An alternative theory has been put forward by Nordin (1958) in an attempt to explain the effect of oestrogens in the context of a general hypothesis that osteoporosis is usually due to calcium deficiency (Nordin 1960). He suggested that the reduction in calcium excretion might be a primary action which would lead, in terms of this hypothesis, to a reduction in bone resorption. It should be possible to distinguish between these two theories quite simply, because if increased net calcium deposition in bone were secondary to a reduction in calcium excretion there should be a slight rise in serum calcium, whereas ifthe reduced excretion were secondary to increased calcium deposition, there should be a slight fall in serum calcium. With this in mind, a retrospective study of the changes in serum calcium and phosphorus in patients with osteoporosis treated with oestrogens was undertaken.