Sexual dysfunction and low testosterone levels have been observed previously in males with chronic noncancer pain treated with intrathecal opioids. To investigate the hypothesis that intrathecal opioids suppress the hypothalamic-pituitary-gonadal axis, a prospective nonrandomized investigation of the function of this axis was undertaken.
Ten males with chronic noncancer pain were evaluated for clinical and biochemical evidence of hypogonadism at baseline and during the first twelve weeks of intrathecal opioid therapy.
Intrathecal opioid administration resulted in a significant (p <0.0001) reduction in serum testosterone, from 7.7 ± 1.1 (mean ± SEM) nmol/L at baseline to 2.0 ± 0.7, 2.8 ± 0.5, and 4.0 ± 0.9 nmol/L at 1, 4, and 12 weeks, respectively. This was associated with a reduction in libido and potency. Luteinizing hormone and follicle-stimulating hormone levels remained within reference ranges, indicating central rather than peripheral suppression.
Administration of intrathecal opioids may result in hypogonadotrophic hypogonadism. As part of the consent for therapy process, patients should be informed about this effect and its management. With long-term intrathecal opioid administration, the hypothalamic-pituitary-gonadal axis should be monitored. Where indicated, testosterone replacement should be undertaken to improve sexual function and prevent the potential metabolic effects of hypogonadism, in particular, osteoporosis.
*Western Australian Pain Management Centre; Departments of †Anesthesia, §Endocrinology, and ∥UWA Department of Medicine, Sir Charles Gairdner Hospital; ¶Department of Biochemistry, The Western Australian Centre for Pathology and Medical Research, Perth; and the ‡Perth Pain Management Centre, South Perth, Western Australia, Australia
Received March 16, 2001;
revised June 30, 2001; accepted November 5, 2001.
L.J.R. was funded by a John Boyd Craig Research Award from the Australian and New Zealand College of Anesthetists.
Please address correspondence and reprint requests to Lindy J. Roberts, Western Australian Pain Management Centre, Queen Elizabeth II Medical Centre, Nedlands 6009, Western Australia, Australia; e-mail: email@example.com