To study the hypothalamic-pituitary-adrenal axis in rheumatoid arthritis (RA) and the influence of glucocorticoid treatment.
Consecutive untreated patients with RA with moderately high inflammatory activity were studied and compared with healthy subjects of similar age. Subjects were studied both at baseline and after multiple releasing hormone (MRH) stimulations. Patients were reexamined one week after starting prednisolone.
The baseline cortisol/adrenocorticotropic hormone (ACTH) ratio was significantly lower in patients with RA. After corticotropin releasing hormone (CRH) stimulation, their serum cortisol response was reduced during the later test phases in spite of intact ACTH response. The baseline and stimulated levels of luteinizing hormone (LH), follicle stimulating hormone (FSH), and thyroid stimulating hormone (TSH) were normal. An impaired prolactin response was seen after MRH stimulation. After one week of prednisolone therapy the absolute response of serum cortisol to CRH was decreased and the stimulated prolactin response was normalized.
Impaired cortisol secretion in patients with RA in the presence of intact ACTH secretion is consistent with relative adrenal glucocorticoid insufficiency. Adrenal impairment may be secondary to the inflammatory disease process.