In thyrotoxic state, a healthy person could maintain a normal serum cortisol level, while some patients may exhibit fatigue, anorexia due to relatively insufficient cortisol caused by excess thyroid hormone, even placing them at risk for adrenal crisis.[10] For example, Nobuyuki Takasu[11]once reported a case that Graves’ hyperthyroidism caused an adrenal crisis in a patient with previously unrecognized non-classical 21-hydroxylase deficiency. Here, TG is linked to classic congenital adrenal hyperplasia due to 21-hydroxylase deficiency.