Potential pitfalls in diagnosis of immunotherapy-induced hypothalamic-pituitary-adrenal axis abnormalities: a clinical case.

Summary: Short synacthen tests (SST) are frequently used for assessing adrenocorticotropin hormone (ACTH) deficiency. In this study, we present the case of a 53-year-old man receiving immunotherapy for metastatic melanoma, who subsequently developed immune checkpoint inhibitor (ICI)-induced hypothyroidism and was investigated for the presence of ICI-induced hypocortisolaemia on different occasions. Despite two reassuring SSTs, he subsequently developed clinical and biochemical evidence of ACTH deficiency.