Role of the hypothalamic-pituitary-adrenal axis in rheumatoid arthritis

ObjectiveA subnormal response of the hypothalamic-pituitary-adrenal (HPA) axis to inflammatory stimuli was found to be associated with the occurrence of chronic arthritis in Lewis rats. This study was carried out to determine the role of the HPA axis in patients with rheumatoid arthritis (RA).MethodsThirty patients with RA of less than 2 years duration were studied. Laboratory tests including ESR, RF and X-ray hands were performed in all patients. All patients were subjected to the standard insulin-induced hypoglycemia test to determine the integrity of the HPA axis. Serum cortisol was estimated at 11 PM on the day prior to the test in eight of these patients.ResultsTwelve out of 30 patients had subnormal cortisol response to insulin-induced hypoglycemia. (normal: cortisol >20 μg/dl and 7 μg > basal cortisol). Two patients had a maximal cortisol response 7 μg > basal but less than 20 μg/dl, i.e. a partial response. Seven patients had a supranormal basal cortisol with no further stimulation with hypoglycemia. Nine patients had an adequate response.Conclusion21/30 (70%) of patients showed some abnormality of HPA axis response. We propose that a primary abnormality of the HPA axis may play a significant role in the pathogenesis of RA.