Serum phosphate and lactate vary with FSH in an early postmenopausal population

We examined serum in recent postmenopausal women to determine the relationship of menopausal status, as FSH level, to serum acid-base balance.

Serum electrolytes of 58 women, aged 53-58, were measured relative to serum FSH. The subjects were over one year since the last menstrual period and were from an academic practice setting.

In women with FSH <35 IU/L (n=20, mean 16.6 IU/L, SD 6.8), phosphate and lactate were reduced relative to women with FSH >35 IU/L (n=38, mean 84.8 IU/L, SD 34.5). No other major anions showed significant differences. Both groups were analyzed by mass spectroscopy for fatty acids and anionic metabolic intermediates. Lactate was the predominant anion in the organic group but accounted for only about 10% of the FSH-responsive anion change. This change was mainly due to a 0.1-mM increase in phosphate in the high FSH group.

There is a direct correlation of early postmenopausal FSH to increasing serum phosphate. Changes in phosphorus may reflect differences in the rate of bone loss.