[Sexual hormones in ageing males (author's transl)].

Alterations of sexual hormones in plasma of ageing males occur between the 50th and 60th year of life with individual variations: 1. Decreased values of testosterone in plasma and a poor response to gonadotrophins demonstrate a diminished synthesizing capacity of the testes in old men. 2. The decreased testosterone plasma values are followed by an increase in LH. The response of the anterior pituitary gland to LH-RH stimulation in old men is normal. 3. Under basal conditions estrone as well as estradiol plasma concentrations increase significantly with age because of increased conversion from androgens. 4. Parallel to estrogen plasma values an increased concentration of the sexual hormone binding globulin (SHBG) is found, resulting in a steep decrease of the free (= active) testosterone fraction. 5. Decreased testosterone, which is more strongly bound to SHBG and increased estrone and estradiol plasma values result in an androgen/estrogen imbalance in old men.