To measure the effect of low-dose systemic glucocorticoid treatment on the adrenal response to adrenocorticotropic hormone (ACTH) in patients with rheumatoid arthritis (RA).
Patients with RA who took part in a randomized double-blind placebo-controlled trial of budesonide (3 mg/day and 9 mg/day) and prednisolone (7.5 mg/day) underwent a short (60-minute) test with injection of ACTH (tetracosactide hexaacetate) at baseline and the day after completing the 3-month treatment program. Plasma cortisol measurements at baseline and 3 months were compared within and between the treatment groups. Individual patients were classified as normal responders to ACTH or as abnormal responders if changes were >2 SD below the pretreatment value in the entire group of study patients.
Short tests with ACTH injection were performed on 139 patients before beginning the study medication and on 134 patients after cessation of the medication. There were no changes in the placebo group. Mean plasma cortisol levels following treatment were reduced in all active treatment groups. In addition, mean values were significantly reduced for the 30-minute and 60-minute responses to ACTH. The maximum reduction (35%) occurred in the prednisolone group at 60 minutes. Following treatment, 34% of patients taking budesonide 9 mg and 46% of those taking prednisolone 7.5 mg failed to reach the normal maximum cortisol response to ACTH. Four patients failed to achieve the normal percentage increase in cortisol levels, but only 1 patient failed to meet both criteria.
Low doses of a glucocorticoid resulted in depression of baseline and ACTH-stimulated cortisol levels after 12 weeks of therapy. Although the responsiveness of the hypothalamic-pituitary-adrenal axis in individual patients generally remained within the normal range, these changes should be investigated further.