A 52-year-old man with chronic hypertension presents with hypokalemia and metabolic alkalosis. He reports daily consumption of large amounts of licorice. Plasma renin and aldosterone are both suppressed. The biochemical basis of his condition is inhibition of which enzyme?
- A 11-beta hydroxylase
- B 11-beta hydroxysteroid dehydrogenase type 2 ✓
- C 21-alpha hydroxylase
- D 17-alpha hydroxylase
Correct answer: B. 11-beta hydroxysteroid dehydrogenase type 2
Explanation
The mineralocorticoid receptor binds cortisol with affinity equal to aldosterone, but renal tubular cells are protected by 11-beta hydroxysteroid dehydrogenase type 2, which converts cortisol to inactive cortisone. Glycyrrhetinic acid from licorice inhibits this enzyme, so cortisol occupies the receptor and causes sodium retention, hypokalemia and hypertension with suppressed renin and aldosterone. Aldosterone levels are low here, ruling out primary hyperaldosteronism, and adrenal steroidogenic enzymes are intact.
Reference: Williams Textbook of Endocrinology, 14th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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