Saturday, July 21, 2018

Topic Discussion: Interesting HTN, hypokalemia and Met Alk syndromes: a summary

There are certain syndromes that lead to HTN, hypokalemia and metabolic alkalosis that are very rare but often confusing. Here is a breakdown of the 3 ones that often can get confusing.

Liddle Syndrome
Missense mutation in ENaC channel

Constitutive activation of the ENaC channel
Triamterene or Amiloride
Low renin and low aldosterone level, no response to spironolactone
Congenital Adrenal hyperplasia
11-B hydroxylase deficiency
Leading to excessive mineralocorticoid production
Life-long steroids to help shut off ACTH
Diagnosis is confirmed by elevations of 11-deoxycortisol and 11-deoxycorticosterone
Glucocorticoid remediable Aldosteronism
Chimeric gene crossover of ACTH and Angio-11 genes
Normal ACTH controls cortisol and AngII controls Aldo. In this gene mutation, ACTH starts controlling Aldo and hence causing HTN and ongoing changes

Leading to excessive aldosterone production.
Life-long steroids to help shut off ACTH

Low renin but high Aldo in these cases.
Syndrome of Apparent mineralocorticoid excess
11-B hydroxysteroid dehydrogenase type 2 mutation or inhibition
Normally, 11-B hydroxysteroid dehydrogenase in-actives cortisol via making to cortisone. This avoids cortisol mediated mineralocorticoid activity to maintain it’s specificity to aldosterone. If this is blocked, then cortisol activates mineralocorticoid activity
Amiloride or spironolactone
Diagnosis made via free urinary cortisol to cortisone ratio
Renin and Aldo levels are low

Licorice that has glycyrrhic acid that can also inhibit 11-B hydroxysteroid dehydrogenase.

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