Adrenal insufficiency in patients on long-term opioid analgesia.

OBJECTIVE: Opioid analgesia has been implicated as a cause of secondary adrenal insufficiency, but little is known of the prevalence of this potentially serious adverse effect in patients with chronic pain. DESIGN: Cross-sectional study of chronic pain patients on long-term opioid analgesia. PATIENTS: Patients attending tertiary chronic pain clinics at the Western General Hospital, Edinburgh, treated with long-term opioid analgesia (n = 48) with no recent exposure to exogenous glucocorticoids. RESULTS: Four patients (8·3%) had basal morning plasma cortisol concentrations below 100 nmol/l, of whom three failed to achieve a satisfactory cortisol response to exogenous ACTH1-24 stimulation (peak cortisol >430 nmol/l). Basal cortisol was positively associated with age (R = 0·398, P = 0·005) and negatively associated with BMI (R = -0·435, P = 0·002). CONCLUSIONS: Suppression of the hypothalamic-pituitary-adrenal axis is present in a clinically significant proportion of chronic pain patients treated with opioid analgesia. Studies of larger populations should be conducted to better define the prevalence and potential clinical consequences of adrenal insufficiency in this context.