CYP21A2 and congenital adrenal hyperplasia: A cortisol response to ACTH exceeding 18 mcg/dL indicates normal hypothalamus–pituitary–adrenal axis activity.[30] Cortisol evaluation is crucial to assess cortisol secretion adequacy, particularly in individuals with Nonclassical Congenital Adrenal Hyperplasia.[31] Prenatal diagnosis is feasible when both parents are carriers of CYP21A2 mutations, typically when they already have a child with 21OHD.