Hypogonadism in patients treated with intrathecal morphine

OBJECTIVE: The objective of this study was to investigate the hypothalamic-pituitary-gonadal response to intrathecal opioids. PATIENTS: Thirty patients receiving intrathecal morphine for chronic nonmalignant pain were studied for clinical and biochemical evidence of hypogonadism. Ten men and 10 postmenopausal women with chronic pain of similar duration but who were not receiving any form of opioid therapy acted as control subjects. RESULTS: Men and both premenopausal and postmenopausal women had evidence of hypogonadism with low levels of serum testosterone or estrogen coupled with low levels of pituitary gonadotrophins. Control subjects had hormone levels in the expected range for their sex and age. Two men demonstrated recovery after ceasing intrathecal opioid therapy. CONCLUSIONS: Hypogonadotrophic hypogonadism is a common complication of intrathecal opioid therapy in both men and women.