[Androgen substitution in the andrological disease picture]

Androgen deficiency is due to an insufficient synthesis of testosterone by the Leydig cells. This is either caused by a primary defect (primary hypoandrogenism) or by an inadequate hypophyseal stimulation (secondary hypoandrogenism). The clinical symptoms may include a late puberty, diminished terminal hairs, small testes, sexual impotence, and abnormal seminal fluid, but none of these conditions as an unique sign allows the diagnosis. This is achieved by low testosterone plasma levels (or low urinary excretion). The primary hypoandrogenism is additionally characterized by high gonadotropin levels, while the secondary form shows low FSH and LH. Hormone substitution is done with hCG and hMG in secondary hypoandrogenism only when fertility is aspired. In all other cases and in primary hypoandrogenism testosterone is given, either as oral form (testosterone undecaonate) or as depot injection (testosterone enanthate). Synthetic derivates like methyltestosterone are hazardous (hepatomas) or, like mesterolone, are too weak in their androgenic effect.