Prednisolone is associated with a worse bone mineral density in primary adrenal insufficiency

Context: Patients with primary adrenal insufficiency (PAI) or congenital adrenal hyperplasia (CAH) receive life-long glucocorticoid (GC) therapy. Daily GC doses are often above the physiological cortisol production rate and can cause long-term morbidities such as osteoporosis. No prospective trial has investigated the long-term effect of different GC therapies on bone mineral density (BMD) in those patients. Objectives: To determine if patients on hydrocortisone (HC) or prednisolone show changes in BMD after follow-up of 5.5 years. To investigate if BMD is altered after switching from immediate- to modified-release HC. Design and patients: Prospective, observational, longitudinal study with evaluation of BMD by DXA at visit1, after 2.2 ± 0.4 (visit2) and after 5.5 ± 0.8 years (visit3) included 36 PAI and 8 CAH patients. Thirteen patients received prednisolone (age 52.5 ± 14.8 years; 8 women) and 31 patients received immediate-release HC (age 48.9 ± 15.8 years; 22 women). Twelve patients on immediate-release switched to modified-release HC at visit2. Results: Prednisolone showed significantly lower Z-scores compared to HC at femoral neck (−0.85 ± 0.80 vs −0.25 ± 1.16, P < 0.05), trochanter (−0.96 ± 0.62 vs 0.51 ± 1.07, P < 0.05) and total hip (−0.78 ± 0.55 vs 0.36 ± 1.04, P < 0.05), but not at lumbar spine, throughout the study. Prednisolone dose decreased by 8% over study time, but no significant effect was seen on BMD. BMD did not change significantly after switching from immediate- to modified-release HC. Conclusions: The use of prednisolone as hormone replacement therapy results in significantly lower BMD compared to HC. Patients on low-dose HC replacement therapy showed unchanged Z-scores within the normal reference range during the study period