The Effect of Endogenous Oestrogen on Plasma and Urinary Calcium and Phosphate in Oophorectomized Women

Using a specific radioimmunoassay, significant levels of plasma oestradiol can be detected in the blood of oophorectomized women. In these women the plasma concentration of oestradiol correlates positively with body fat content. Low circulating concentrations of oestradiol are associated with increased values for serum phosphate and alkaline phosphatase, but no significant change in serum calcium. The fasting urinary calcium creatinine ratio is inversely related to circulating plasma oestradiol concentration which also correlates, in a more complex way, with the renal threshold for phosphate (TmPO4/GFR). It is suggested that oestrogen production may be an important factor in determining bone loss in postmenopausal women.