The adrenal gland secretes a basal level of cortisol but can also produce bursts of the hormone in response to adrenocorticotropic hormone (ACTH) from the anterior pituitary. Cortisol is not evenly released during the day – its concentrations in the blood are highest in the early morning and lowest in the evening as a result of the circadian rhythm of ACTH secretion. Cortisone is an inactive product of the action of the enzyme 11β-HSD on cortisol. The reaction catalyzed by 11β-HSD is reversible, which means that it can turn administered cortisone into cortisol, the biologically active hormone.
the adrenal GlAnd Secretes a Basal leVel of cortisoL buT CaN also PROduce bursts oF the hormOnE IN rEspOnse To aDrENocorticotropic horMoNe (Acth) from the AnterIor pITUItary. COrtisoL iS nOt EVenlY rELeaSeD durIng the dAy – ITS coNCEntratIonS in the blood arE hiGhest In ThE earlY MOrNiNG anD LOwest in thE eveNiNg as a rESulT OF the CircAdiaN rhyThm Of aCth sEcretiON. cortisone is An inacTive prODuct oF the ACtiON oF thE enZymE 11β-hsd on cortisol. ThE REacTion caTaLyzEd By 11Β-hsd Is reVeRsibLe, wHich MEans THat it can turn aDMinIstEred coRtIsOne iNtO cOrtiSOL, The biOlogiCAlLy active hOrmONe.