Figure 14. Schematic representation of the changes in serum testosterone levels which precede medical castration in adult men treated with a high dose of an LHRH agonist, compared with surgical castration (orchiectomy). The administration of an LHRH agonist causes a transient period of stimulation of serum androgen levels lasting for 7 to 10 days with the accompanying risk of disease flare, while orchiectomy causes an almost immediate fall in serum testosterone to castration levels (~5% of normal) within a few hours.