Which corticosteroid is indicated for adrenal cortical insufficiency?

Hydrocortisone is indicated for adrenal cortical insufficiency because it is a synthetic version of cortisol, a hormone produced by the adrenal glands. When the body is unable to produce sufficient levels of cortisol, often due to conditions like Addison's disease, hydrocortisone supplementation is necessary to help manage the symptoms and maintain homeostasis. It acts to replace the natural hormone, supporting various bodily functions such as metabolism, immune response, and stress responses.

The other options are not appropriate for treating adrenal cortical insufficiency. Chlorthalidone is a diuretic used primarily for hypertension and edema, not for hormone replacement. Metformin is an oral hypoglycemic agent used to manage type 2 diabetes, while furosemide is another diuretic, primarily used for fluid retention and heart failure. Thus, they do not address the specific hormonal deficiencies related to adrenal cortical insufficiency.