What is secondary adrenal insufficiency?

ACTH deficiency Acquired (iatrogenic - sudden cessation of exogenous cortisol/ treated Cushing's after adenoma removal/ hypopituitarism/ isolated ACTH deficiency) Inherited causes (isolated defect in TPIT mutation (promoter of POMC)/ post-translational defect processing POMC to ACTH by prohormone convertase 1 or 2 (PC1/2 mutation)/ POMC gene mutation (red hair pigmentation due to decreased MSH)