POMC and Adrenal insufficiency: It is classified into 3 types: (a) absolute adrenal insufficiency (low plasma cortisol levels at <100 ng/mL, ref. 3); (b) relative adrenal insufficiency (RAI), defined by insufficient production of cortisol relative to organ demand and diagnosed with a change in cortisol (Δcortisol) of less than 90 ng/mL after an adrenocorticotropic hormone (ACTH) test (4); and (c) glucocorticoid (GC) resistance (impaired cellular GC signaling) (5).