Endocrine consequences of opioid therapy.

Gonadal hormones are known to be affected by morphine and other opioids. In this paper, we summarize data collected in recent years which clearly indicate that the opioid-induced effects on steroid hormones depend on the opioid used and in some cases on the sex of the subject. Indeed morphine is able to reduce hormones like testosterone and cortisol in both male and female subjects in just a few hours, probably acting directly on peripheral glands. These depressant effects of morphine on hormones are also present in the treatment of surgical pain and are quickly reversible once opioid administration is suspended. Similar actions were also found to occur in experimental animals and in vitro in glial cells, further confirming the morphine-induced reduction of testosterone cell content. Testosterone and its metabolites are well known substances involved in the development and maintenance of the brain and all body structures. Thus when treating pain with opioids, their effects on hypothalamo-pituitary-gonadal and hypothalamo-pituitary-adrenal-related hormones must be considered and, where possible, hormone replacement therapy should be started.