11-beta-hydroxysteroid dehydrogenase normally degrades cortisol to cortisone. In some patient's with Cushing's Syndrome there is a state of relative mineralocorticoid excess, which is associated with reduced activity of 11-beta-hydroxysteroid dehydrogenase.


Clinical features:

(1) hypertension

(2) hypokalemia


Laboratory findings in a 24 hour urine:

(1) increase in urine cortisol concentration relative to urine cortisone

(2) increased ratio of (tetrahydrocortisol plus 5-alpha tetrahydrocortisol) to tetrahydrocortisone


ratio of tetrahydrocortisol and 5-alpha tetrahydrocortisol to tetrahydrocortisone =

= ((urine tetrahydrocortisol in mg per day) + (5-alpha tetrahydrocortisol in mg per day)) / (tetrahydrocortisone in mg per day)



• A normal patient has a ratio of 0.51 to 1.47 (mean 0.81).

• A patient with pituitary Cushing's syndrome has a mean value of 1.49.

• A patient with adrenal Cushing's syndrome has a mean value of 1.85.

• A patient with ectopic ACTH has a mean value of 4.12. These patients also have a marked increase in excretion of all cortisol metabolites.


To read more or access our algorithms and calculators, please log in or register.