COPD and hyponatremia

[NYyanx28]

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Can't find much info aside from just SIADH without any explanation or other logical causes. Help?

 

[jdh71]

Can't find much info aside from just SIADH without any explanation or other logical causes. Help?

What's the context?

 

[Chloroform4Life]

Maybe it's not COPD but Legionella pneumonia. But many things can cause hyponatremia, you need to expand.

 

[NYyanx28]

Can't find much info aside from just SIADH without any explanation or other logical causes. Help?

Whoops my bad. My question was the mechanism behind hyponatremia in the context of COPD. Many sources list the etiology of hyponatremia/euvolemia in COPD/lung disease in general as SIADH, but I'm not sure how to connect the dots between lung disease and fluid retention.

 

[jdh71]

Whoops my bad. My question was the mechanism behind hyponatremia in the context of COPD. Many sources list the etiology of hyponatremia/euvolemia in COPD/lung disease in general as SIADH, but I'm not sure how to connect the dots between lung disease and fluid retention.

Nor is anyone else unfortunately. It's just as associated phenomenon, lung pathology, any lung pathology, and SIADH.

Of course you can also retain fluid via plumonary hypertension and right heart failure within the context of COPD, and get a secondary hyponatremia from a cardio-renal syndrome type of picture . . . effective blood flow to the kidneys is down, they active RAAS, take up water.

 

[Laryngophed]

i'd blame it on licorice.

 

[jdh71]

i'd blame it on licorice.

Don't laugh. That WILL be a test question.

 

[Laryngophed]

Don't laugh. That WILL be a test question.

I know, that's why I threw it out there. I'm a grad student and one of my courses this past semester entailed getting basic scientists over their "fears" and reading clinical papers. I had one about just this thing and one of my lab mates has a medical degree in traditional Chinese medicine and mentioned that she's prescribed licorice and licorice oil for any number of lung "issues." I mentioned it to a buddy of mine that is an M2 and he told me to memorize and put it in my trivia bank, I'll need to regurgitate it soon.

 

[VanBrown]

In short, being chronically hypercapnic REDUCES renal blood flow, which results in increased water and sodium retention. This results in a dilution effect for sodium and registers as hyponatremia (SIADH).

Treat with IV saline and monitor to make sure it isn't due to another cause, but usually in a long-standing COPD patient with an acute exacerbation this is what you'll see. Lab values are usually like 125-130 so it isn't really striking but its something to keep an eye on.