A 60-year-old man comes to the physician because of ...
Urine Na+: increased; Serum osmolality: decreased
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.