The effects of age and body composition on circulating serum oestrogens and androstenedione after the menopause.

Circulating levels of oestrone, oestradiol and androstenedione were measured in two large groups of postmenopausal women, in one group the women were between 46 and 56 years of age and in the second, older group they were 70 years of age. In addition the fat mass was calculated from the height, weight and age of the women. Serum concentrations of both oestrogens did not change with age, whereas the serum androstenedione concentration decreased significantly. A change in body composition included decreased height and increased fat mass in the older group. Serum concentrations of both oestrogens correlated significantly with the fat mass and serum androstenedione as well as with each other. From the correlation analysis it may be concluded that the conversion rate of androstenedione to oestrone, and of oestrone to oestradiol, increases with age, which presumably explains the unchanged concentrations of the circulating oestrogens in relation to postmenopausal age, although the precursor decreases during the same period.