Hyponatremia and Legionella Pneumonia

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notarealname

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I understand there was a post like this in the past, but I hope someone can give me a better explanation on this.

An old post http://forums.studentdoctor.net/showthread.php?t=712781

I would like to know the exact mechanism for Legionella Pneumonia pts to have hyponatremia and why is it unique in this case not in other infections or diseases?

Thank you!
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Legionella produces an interstitial disease that can destroy the JG apparatus, so you can't secrete renin. Without renin, you can't make aldosterone, so you get a type IV renal tubular acidosis and can't reabsorb Na.

Theoretically TB could do the same by invading the adrenal gland and causing Addison's.
 
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justinbaily said:
Legionella produces an interstitial disease that can destroy the JG apparatus, so you can't secrete renin. Without renin, you can't make aldosterone, so you get a type IV renal tubular acidosis and can't reabsorb Na.

Theoretically TB could do the same by invading the adrenal gland and causing Addison's.
Click to expand...

Thanks a lot for this most perfect explanation!
 
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JustinBaily hit the nail on the head. If you read Goljan RR he has it laid out perfectly. L. pneumophila can destroy the JG apparatus and thus the patient will not secrete renin (since the juxtaglomerular (or granular) cells are responsible for the production, storage, and release of renin), so if the patient doesn't have renin, they will not have angiotensin I, and then won't have angiotensin II, and then won't have aldosterone and thus won't reabsorb Na+ (or secrete K+, so expect hyperkalemia). So to recap, they won't have renin (thus HYPORENINEMIC) or aldosterone (thus HYPONATREMIA) so the patient will end up with hyporeninemic hyponatremia. Type IV RTA is characterized by either aldosterone deficiency or resistance so, yes, it could also lead to a Type IV RTA with a normal anion gap (hyperchloremic) metabolic acidosis.

Goljan RR to the rescue!

Also, don't forget the fact that the patient will likely be elderly, a smoker, immunocompromised, etc., and may also have diarrhea and/or confusion/mental changes presenting as a textbook L. pneumophila pneumonia.
 
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MrBeauregard said:
JustinBaily hit the nail on the head. If you read Goljan RR he has it laid out perfectly. L. pneumophila can destroy the JG apparatus and thus the patient will not secrete renin (since the juxtaglomerular (or granular) cells are responsible for the production, storage, and release of renin), so if the patient doesn't have renin, they will not have angiotensin I, and then won't have angiotensin II, and then won't have aldosterone and thus won't reabsorb Na+ (or secrete K+, so expect hyperkalemia). So to recap, they won't have renin (thus HYPORENINEMIC) or aldosterone (thus HYPONATREMIA) so the patient will end up with hyporeninemic hyponatremia. Type IV RTA is characterized by either aldosterone deficiency or resistance so, yes, it could also lead to a Type IV RTA with a normal anion gap (hyperchloremic) metabolic acidosis.

Goljan RR to the rescue!

Also, don't forget the fact that the patient will likely be elderly, a smoker, immunocompromised, etc., and may also have diarrhea and/or confusion/mental changes presenting as a textbook L. pneumophila pneumonia.
Click to expand...

Wow, thanks a lot very thoroughly done!
 
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notarealname said:
I understand there was a post like this in the past, but I hope someone can give me a better explanation on this.

An old post http://forums.studentdoctor.net/showthread.php?t=712781

I would like to know the exact mechanism for Legionella Pneumonia pts to have hyponatremia and why is it unique in this case not in other infections or diseases?

Thank you!
Click to expand...
I am searching for this myself. All I have found so far is that these previous posts are all incorrect. At one time it was assumed that the mechanism for Legionella causing hyponatremia had to do with kidney failure --> reduced aldosterone. But these posts are really old, and researched published by NIH in 2012 showed that ADH levels were normal in Legionella patients who were hyponatremic. So the search is still on. Anyway, I think since even researchers don't know the mechanism, its not likely to be tested.
 
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Dixe Reb said:
I am searching for this myself. All I have found so far is that these previous posts are all incorrect. At one time it was assumed that the mechanism for Legionella causing hyponatremia had to do with kidney failure --> reduced aldosterone. But these posts are really old, and researched published by NIH in 2012 showed that ADH levels were normal in Legionella patients who were hyponatremic. So the search is still on. Anyway, I think since even researchers don't know the mechanism, its not likely to be tested.
Click to expand...
Oops, here's the reference: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3363562/
 
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Dixe Reb said:
Swiss researchers in 2014 concurred that ADH level was not related to the hyponatremia of Legionella.
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The previous quotes say literally nothing about ADH. They're all taking about the RAAS. (Renin, angiotensin, aldosterone) no reference was ever made here to the pituitary or ADH (vasopressin).

... That is, until you brought up ADH.
 
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