The results of the Intersalt Study did not indicate any clear pattern between the level of salt intake and blood pressure in those countries studied. (23) And when average life expectancy is plotted against the countries average salt intake, the trend shows that higher salt consumption is actually correlated with longer life expectancy. While this correlation does not imply causation, it is interesting to note the compatibility of a high salt diet with a long life expectancy.
You eat whole foods, and add some salt here and there, you will be hard pressed to eat "too much" salt, and if you do, your healthy kidneys will easily flush the extra. Best way to get into trouble with your kidneys is by becoming diabetic. The cascade of nasty that accompanies uncontrolled blood sugars is causing renal failure on a large scale - that's why you see so many dialysis centers all over the place.
Best way to heal a kidney damaged by diabetes or metabolic syndrome? Carb restriction. Even the ADA recommends that for weight loss for up to a year (after that, I suppose you are supposed to go back to the high carb diet that almost killed you the first time).