Serum cortisol level to screen for significant hypothalamic–pituitary–adrenal axis suppression in patients receiving multiple steroid injections

Morning serum cortisol level (mSCL) is a practical screening tool for hypothalamic-pituitary-adrenal (HPA) axis suppression and has been used to assess for duration of cortisol deficiency after epidural and peripheral glucocorticoid injections. More evidence is needed to establish utility of mSCL in patients undergoing repeat injections with increasing cumulative-glucocorticoid-equivalent-dose (CGED) that may place them at higher risk for HPA axis suppression.To estimate the prevalence of spine injection candidates with significant HPA axis suppression (sigAS), to understand the correlation between 12-months of CGED and presence of sigAS based on timing of mSCL collection from latest glucocorticoid injection (within 6-weeks, or between 6-weeks and 12-months), and to investigate demographic and clinical factors relating to sigAS.Retrospective chart review of patients scheduled for spine injection who had an associated mSCL and documented histories of prior glucocorticoid injections. The steroid name, dose, type, and procedure location were recorded for each injection within 12-months prior to mSCL. CGED was calculated based on standard glucocorticoid-equivalent conversion factors.SigAS was present in 7.8% to 22% of the analysis cohorts. There was no association found between CGED and sigAS regardless of timing of mSCL. There was a trend toward lower mSCL and sigAS with increasing CGED. There were no significant relationships found between sigAS and overall demographic or clinical factors.A three-fold reduction in the rate of sigAS was noted six weeks after the most recent steroid injection. Using mSCL provides a template to investigate the impact of CGED and best timing for mSCL collection in order to define a more practical guideline to identify patients at higher risk for sigAS earlier and plan for future spine injections.