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Why would body respond to water retention with ALDO? ALDO would increase water retention...
@hello, the body's response is to decrease Aldosterone since there is increased volume retention and subsequently increased blood pressure.
This concept confused me a lot, but I ended up just viewing it as separate responses. First, the increased volume retention leads to increase ANP and BNP secretion that lead to decreased Na+ reabsorption in the tubules (page 294 in FA 2019) and second, this increased volume basically leads to increased pressure so lets also decrease aldosterone so there is no Na+ retention (since water comes with it)...
I thought it was counterintuitive to secrete so much Na+ since you're already having decreased serum osmolality (decreased Na+ concentration) because of the water retention, but I'm guessing that this is just another way our body's well intentions end up making us worse XD
see page 344 FA2019 for SIADH.
author pasted text straight from FA but the arrows didn't copy over, inverting the original meaning
The idea of increasing urine Na is getting rid of water, thats why this mechanism end increasing urine Na secretion even when there are very low serum Na levels.