Long‐term intrathecal morphine influence on major compounds of the endocrine system in elderly population

Abstract Background The influence of long-term opioid administration on hormonal levels is not well characterized in the literature. We previously showed that intrathecal opioid therapy significantly influences the homeostasis of immune and endocrine systems. Other authors confirmed that exogenous and endogenous opioids induce this effect. They have a cytokine-like behavior and may function as neurotransmitters, neuromodulators or hormones, as concerning their synthesis, storage and release. Aims To assess the effects of morphine long-term intrathecal administration on serum levels of Gonadal, Thyroidal and Adrenal axis hormones in an elderly population affected by chronic pain; to assess the correlation between hormone levels and morphine dosage. Methods Patients suffering from chronic non-cancer pain with or without intrathecal drug delivery system were studied and hormonal levels were monitored, using an immunoradiometric assay kit. Results The long-term administration of intrathecal morphine influenced part of the endocrine system, in particular, there was a reduction of FSH and LH and an increment of GH serum levels; this effect was morphine dose dependent. Conclusion Long-term intrathecal opioid administration influenced FSH, LH and GH serum levels. Data on this issue are inadequately described in the literature. The finding of endocrine effects of opioid therapy, nonetheless, cannot be ignored, as it may have clinical relevance in both elderly and young population. We believe that during long intrathecal pain treatments with morphine, clinicians should be aware of both immediate and later opioids side effects, and in particular, they should monitor immune and endocrine changes.