Background: Glucocorticoid-induced osteoporosis is one of the major clinical concerns of long-term steroid treatment. Previous studies have shown that immunosuppressive doses of glucocorticoid can lead to osteoporosis. This study investigated whether there is a relationship between cortisol exposure and the development of osteoporosis in patients receiving replacement doses.
Methods: Hydrocortisone day curves (HCDCs) performed at Imperial College Healthcare NHS Trust between 2004 and 2012 were analysed. The area under the curve (AUC) cortisol was calculated for each patients day profile and dual-energy X-ray absorptiometry (DEXA) scans were obtained from PACS imaging system, both at the time of HCDC and after five years for each patient. The change in mean bone mineral density (BMD), T-score and Z-score in the L2L4 segment over five years was recorded (n=24, 16 females, 8 males).
Results: The mean age of the patients was 56.6 years (95% CI 51.2-62.01). The AUC cortisol did not significantly correlate with the baseline mean BMD (r=−0.25, P=0.23), T-score (r=−0.21, 0.33) or the Z-score (r=0.05, P=0.83) in the L2L4 segment. This study found no significant correlation between the AUC cortisol and the change in mean BMD of the L2-L4 segment (r=−0.12, P=0.56), the change in T-score (r=−0.16, P=0.44) or the change in Z-score (r=−0.31, P=0.15) score in the L2L4 segment over five years.
Conclusion: This pilot study has found no association between replacement cortisol exposure and mean BMD in patients receiving long-term steroid replacement although there may be a true relationship between higher cortisol exposure and the development of osteoporosis. It is known that decreasing the hydrocortisone dose decreases osteocalcin so it is necessary to investigate whether higher cortisol exposure disproportionately affects bone architecture compared to BMD.