9a-Fluoro-17-hydroxycorticosterone, Fluohydrisone, Astonin H; (8S,9R,10S,11S,13S,14S,17R)-9-fluoro-11,17-dihydroxy-17-(2-hydroxyacetyl)-10,13-dimethyl-6,7,8,9,10,11,12,13,14,15,16,17-dodecahydro-1H-cyclopenta[a]phenanthren-3(2H)-one

Fludrocortisone is a synthetic corticosteroid with moderate glucocorticoid potency and much greater mineralocorticoid potency. Therapeutically, it is used for its mineralocorticoid activity and not for its glucocorticoid activity. Fludrocortisone has been used in the treatment of cerebral salt wasting syndrome. However, it is used primarily to replace the missing hormone aldosterone in various forms of adrenal insufficiency such as Addison's disease and the classic salt wasting (21-hydroxylase deficiency) form of congenital adrenal hyperplasia. Due to its effects on increasing Na+ levels, and therefore blood volume, fludrocortisone is the first line of treatment for orthostatic intolerance and postural orthostatic tachycardia syndrome (POTS). It can be used to treat low blood pressure. Fludrocortisone is also used as a confirmation test for diagnosing Conn's syndrome (aldosterone producing-adrenal adenoma).