[The endocrine basis of sexual dysfunction in the elderly]

There are no direct associations between testosterone levels and sexual function in the aging male. A study of 169 patients focusing on the relations of hormone levels and sexual dysfunction did not reveal associations between testosterone levels and the risk of altered sexual functions. In volunteers, in whom a hypogonadism was generated by the application of GnRH, no alterations in sexual reactions occurred. It is possible that other testosterone fractions are more meaningful than the total testosterone. However, all the known fractions correlate closely. The significance of a normal testosterone level for a normal erection has been rarely considered up to now. In an animal experiment, the intracavernous pressure, the density of alpha-receptors, and the PDE5 activity depended on normal testosterone levels. It is not known whether different testosterone levels influence the effectiveness of treatment procedures for erectile dysfunction in humans. The following questions with practical consequences have to be answered: Is the extensive determination of the bioactive testosterone necessary? Does the efficacy of treatment for erectile dysfunction depend on testosterone levels?