Serum sex hormone binding globulin in prepubertal girls and adult women.

Serum SHBG concentration depends on the hormonal status. Androgens decrease while estrogens increase SHBG biosynthesis in the liver. In the present study an attempt was made to investigate whether the changes that occur in the ratio of estrogen to androgen concentration between prepubertal girls and women could have influenced plasma SHBG levels. For this reason serum concentrations of SHBG, E2, T and DHEA-S were measured in 31 girls, aged 4.5-9 years, at Tanner stage I of pubertal development, and in 24 normal women. The girls were divided into 2 groups of different ages. The concentrations of non-SHBG-bound E2 and T and free E2 and T were calculated. The results showed a negative correlation between SHBG serum levels and the age of prepubertal girls while the ratio of E2/T did not change. Although the ratio of E2/T was found increased by 10 times between older prepubertal girls and women in the luteal phase of menstrual cycle, serum SHBG levels only slightly decrease in the group of women. The non-SHBG-bound E2 and free E2 levels were significantly higher in women than those in prepubertal girls indicating an increase of estrogen milieu in target tissues. It seems that apart from the changes that occur in the ratio of E2/T the serum SHBG levels may be also under the control of other factors.