Why do humans have two glucocorticoids: A question of intestinal fortitude

Corticosterone has significantly lower Km's for both 11β-HSD2 and 11β-HSD1 enzymatic dehydrogenase activity, compared to cortisol. Patients diagnosed with 17α-hydroxylase deficiency have elevated blood pressure and high levels of circulating corticosterone, 3α,5α-TH-corticosterone, and their 21-dehydroxlated corticosterone derivatives. In humans, these 5α-corticosterone metabolites are likely to influence blood pressure regulation and Na+ retention by inhibiting the rate of deactivation of cortisol by 11β-HSD isoforms.