Hypothalamus-Pituitary-Adrenal (HPA) axis Besides neural mechanisms, also hormonal abnormalities could cause altered pain processing. Cortisol is released in answer to pain to suppress the pain. Given the evidence for hypofunction of the hypothalamic-pituitary-adrenal axis and the lower cortisol release in response to stressors in a proportion of FM patients and in chronic whiplash associated disorders (WAD) patients, the relation between pain and cortisol in these patients may be an interesting topic to consider.