Early menopausal changes in bone mass and sex steroids.

Eighty-four healthy perimenopausal and early postmenopausal women were divided into four groups: group A, those with slightly irregular menstrual periods and plasma FSH below 40 mIU/ml; group B, those with irregular periods and FSH above 40 mIU/ml; group C, those whose last menstrual period was within 1 yr of study; and, group D, those whose last menstrual period was between 12 and 55 months before the study. Plasma concentrations of estrone and estradiol progressively decreased in groups B, C and D compared to those in A in parallel with a decrease in the production rates, and FSH and LH were significantly increased. There was little change in the concentration of androstenedione or testosterone. Vertebral bone mass was significantly decreased in groups B, C, and D compared to that in A, and radial bone mass was decreased in group D. There was a significantly positive correlation between plasma estrone and estradiol and bone mass at both the radius and vertebra. Increased bone remodeling was suggested by increases in serum calcium and bone gla protein. These data suggest that bone loss, at least from the spine, may begin before menses cease and is correlated with decreases in estrogen production and increases in bone remodeling.