So, we snack like crazy on junk food loaded with sodium. I understand the body is geared to retain sodium, so where does it all go? Are we all just walking pillars of salt (or saline)?
Bonus Question: Does drinking water at above rec’d levels allow us to excrete sodium?
Junk food is not the only source of sodium. The body is not geared to retain sodium; it’s geared to maintain it in equilibrium with the rest of the body composition. Excess sodium is eliminated in the urine (natriuresis). It seems to be the case that chronic intake of excessive amounts of sodium raises blood pressure; lowering intake lowers blood pressure, with a more marked effect in African Americans, perhaps. A given sodium load is simply peed off if you have normal renal physiology.
Diets that are relatively high in sodium are thought to result in disorders such as high blood pressure. The assorted feedback loops for sodium homeostasis are understood in a fair amount of detail but the underlying reason for the relationship between sodium and hypertension is not.
The human body must expend some free water to get rid of sodium. However drinking extra free water will not necessarily prevent those who have excess sodium intake from having problems. I am not aware if a study has been done on that particular idea, though.
No doubt, Chief, you are knowledgeable in this area. I was under the impression that, simply put, the kidney uses sodium to maintain the gradient to pull everything out of the bloodstream and then put it back - except for the waste. I was also taught that urine is concentrated because the kidney uses sodium to retain water. Thus, urine does not contain as much water as people would think.
In short, isn’t it empirical that the body must retain (a majority of) sodium, or else it wouldn’t be such a health issue or, would it? Maybe this is all oversimplified? Can you help correct me & explain further? 
Thanx, Jinx
Please let me off the hook here, since sodium homeostasis is confusing even to medical students. When they finally think they’ve got it, they meet real patients and everything they’ve learned about renal physiology seems to go out the window. 
The best snippet summary I can think of is this remark: “Sodium homeostasis: (is a series of) Steady states without a set point.” http://www.nature.com/ki/journal/v21/n6/abs/ki1982113a.html
In other words, the body gets used to a certain input/output for sodium and water, and excess sodium input will be discarded while decreased input will result in conservation. However, various factors–poorly understood–can create new “set points” for homeostasis.
It’s true that free water clearance depends on sodium gradients at the level of the nephron(look up “nephron” if you want to research further, but that’s just the actual cellular machinery responding to signals and feedback loops from elsewhere in the body.
I suggest you find some good articles using the search term “sodium homeostasis” and start there. I have to get back to bitching about your suggestion that we get more banking regulation. 