I have craved salt since childhood. A grandmother used to say that I would "dry my blood up"! However, since suffering two episodes of severe hyponatraemia (down to 115 mmol/litre, which is near life-threatening) I have abandoned any attempt to reduce my salt intake and instead make sure to have plenty. Increasing salt intake has not increased my blood pressure at all. (I was diagnosed hypertensive several years ago, cause unknown, and it is quite well-controlled with an ACE inhibitor.)
When I was in hospital with severe hyponatraemia my urine sodium was not tested ONCE. Convinced that I was losing the sodium in urine, contrary to the ridiculous diagnoses the doctors insisted on, I eventually got my GP to test my urine sodium and my blood sodium. Blood sodium was below normal, but there was quite a lot in my urine.
What the docs should really do is calculate the Fractional Excretion of Sodium (FENa), but of course they didn't, and they didn't test the other parameters needed to do this, so I couldn't do it myself either.
I would recommend anyone concerned about their salt intake to have their serum sodium checked, and ideally also the other tests referred to here:
http://www-users.med.cornell.edu/~spon/picu/calc/fenacalc.htm
If docs don't know how to interpret the results, get the figures yourself, do the sums and find out what your result means. Doctors (at least in the UK) don't seem to have a clue.
Research on links between salt intake and various chronic conditions has had conflicting findings, and until I see some that measures serum sodium instead of just urine sodium I can't attribute any relevance to it. Using just urine sodium to estimate sodium intake is bizarre, as some of the subjects may well actually be hyponatraemic, precisely because they are losing so much in urine, rater than consuming too much salt.
There has been some recent research that found links between sodium intake and autoimmunity, but it was just
in vitro and in mice, so may not apply to humans. The abstract is here:
http://www.nature.com/nature/journal/vaop/ncurrent/full/nature11868.html