Primary hypoaldosteronism

[MudPhud20XX]

Primary hypoaldosteronism results from a decrease in adrenal secretion of aldosterone. Which of the following would be expected to accompany this disorder?
A. Decreased plasma K+
B. Decreased plasma renin
C. Increased extra-cellular fluid volume
D. Increased plasma angiotensin II
E. Increased plasma Na+

Answer: D

I chose B. My reasoning was that low renin could be the cause for the hypoaldosteronism due to the failure of feedback of sensing low aldosterone.

If D is the correct answer then why would you get hypoaldeosteronism? Is it b/c the defective zona glomerulosa? I am a bit confused here and would appreciate any help. Many thanks in advance.

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[Enzymes]

Primary implies the problem is in the adrenal. So the Renin angiotensin system is fine. For whatever reason, you are unable to produce aldosterone (maybe there is a synthesis problem in the adrenal cortex).

 

[teotuf]

The question was asking about PRIMARY hypoaldosteronism. I.e. what does low aldosterone cause, not what causes low aldosterone.

If you start with low aldosterone, you'd get a compensatory increase in renin/angiotensin to try to maintain homeostasis. It's analogous to the fact that you'd have increased serum TSH level in Hashimoto's thyroiditis or any primary hypothyroidism problems.

 

[thehundredthone]

Very important concept, the difference between primary and secondary disorders. Especially when there are feedback mechanisms in place. It's like (but not exactly) T4 and TSH in primary and secondary hypothyroidism.