To assess the status of the hypothalamic-pituitary-adrenal (HPA) axis in cortico-steroid-treated patients whose prednisone dose had been tapered to physiologic doses.
The design of the study was a retrospective chart review of 50 consecutive patients receiving 10 mg or less of prednisone daily at a university teaching hospital rheumatology clinic. Patients were given a rapid adrenocorticotropic hormone stimulation test, with cortisol levels obtained at baseline and after intravenous administration of cosyntropin. Charts were reviewed for duration of therapy, highest, current, and total cumulative steroid dose, and average daily steroid dose in each month of the preceding 2 years.
Current steroid dose was the only significant indicator of HPA axis function. Patients receiving less than 5 mg of prednisone daily had a normal HPA axis response, whereas those receiving 5 mg or more had widely varied responses. Neither the total, the highest prednisone dose, nor the duration of therapy was a significant indicator of HPA axis recovery.
Spontaneous recovery of the HPA axis is usual for patients who are taking prednisone at daily doses of 5 mg or less. Return of normal HPA axis function can be achieved without alternate-day therapy in patients whose disease allows tapering to daily prednisone doses of 5 mg or less.