Wow 2 tablspns is alot of salt. I might use 1/2 tspn per day from all sources. My blood pressure is most always really low also.
Blood tests and tissue tests seem to vary greatly. The blood will do everything in its power to keep within normal levels. It will take what it needs above all else. I'm sorry I don't have a better answer for you but maybe someone else will explain it better than I can.
All I know is that the higher my sodium/potassium levels climb on my hair analysis the better I feel.