The ACTH test fails to diagnose adrenal insufficiency and increases cytokine levels in septic conditions

The ACTH test is used to diagnose relative adrenal insufficiency (RAI) or critical illness-related corticosteroid insufficiency (CIRCI). Initially, guidelines recommended corticosteroid/glucocorticoid (GC) therapy for septic patients with RAI, but later trials did not show a survival benefit, leading to updated guidelines that abandon targeting RAI or CIRCI. Recent studies with an RAI mouse model showed a clear survival benefit from GC therapy in mice with RAI, suggesting that the inconclusive GC clinical trials might be due to issues with the ACTH test rather than targeting RAI. To investigate, we performed the ACTH test in septic mice. Interestingly, the ACTH test identified most mice as having adrenal insufficiency in the early and middle stages of sepsis, even those with a normal adrenal stress response. Surprisingly, the ACTH test triggered inflammatory cytokine to lethal levels, moderately increased mortality in septic mice. Mechanistically, RNAseq analysis revealed that these cytokines were generated by the adrenal gland via AP-1 signaling. These findings suggest that the inconclusive results of GC therapy trials may be due to the problematic nature of the ACTH test rather than the ineffectiveness of targeting RAI/CIRCI.