Opioid endocrinopathy: A clinical problem in patients with cancer pain

Opioids are commonly used in cancer pain management. The present study aimed to investigate the occurrence of endocrine dysfunction in patients with cancer pain treated with opioids. The study included 20 patients with cancer-associated pain. All data were obtained from malignant tumors diagnosed and followed up at the Oncology Clinic of Akdeniz University Hospital (Akdeniz, Turkey) between May 2009 and December 2013. Serum samples were collected to determine the levels of hypophyseal, gonadal and thyroid hormones. The inclusion criteria for the study were as follows: Chronic cancer pain, daily treatment with a morphine equivalent daily dose (MEDD) of ≥25 mg/dl for ≥1 month, and a visual analog score of <2. All independent predictors were evaluated using logistic regression analysis. The results did not demonstrate any significant association between MEDD and gender, or the levels of adrenocorticotropic hormone, cortisol, prolactin, thyroid-stimulating hormone, free thyroxine, follicle-stimulating hormone and luteinizing hormone. However, the levels of testosterone (P=0.040) and of free testosterone (P=0.041) were significantly affected by the MEDD. Conversely, prolactin levels were demonstrated to significantly increase with MEDD (P=0.083). The results also indicated that the required opioid analgesic dose and MEDD were significantly affected by age (P≤0.001). Opioid therapy in patients with cancer may inhibit gonadal function and cause hyperprolactinemia.