11ß-hydroxysteroid dehydrogenase is an enzyme that inactivates cortisol to cortisone at the mineralocorticoid receptor.
This prevents cortisol from mimicking the action of aldosterone. Deficiency of this enzyme therefore allows excessive stimulation of these receptors by cortisol, resulting in raised blood pressure due to sodium retention in the kidney.
11ß-hydroxysteroid dehydrogenase deficiency may be inherited or acquired.
This inherited disorder results in hypertension (high blood pressure) and hypokalaemia (low blood potassium levels) as a result of the excess mineralocorticoid activity in the kidney.
The aim of the treatment is to suppress the cortisol levels and hence prevent activation of the mineralocorticoid receptor.
Chronic ingestion of glycyrrhetinic acid, the active ingredient of liquorice, will result in the inhibition of 11ß-hydroxysteroid dehydrogenase activity. This will allow glucocorticoids to exert their effects on the mineralocorticoid receptors and produce the hypertension and hypokalaemia (as described above in the hereditary deficiency).