The first thing my doctor wants me to do is reduce fluid intake since he believes 124 oz per day is a lot and that could be the cause. There has bee no talk of any other treatment or investigation yet -- we'll do this first and go from there.

I was once on Hcl for a couple of weeks which sent my sodium down to 124, so I went off that, as per Sue's point above.

I think the key thing to keep in mind when considering my case is that my sodium has been low since the previous century, and that is regardless of what meds I was on or not on over these many years, and that I've never experienced any obvious problems and live an active life of weight lifting, playing tennis, softball, etc. (That said, it's possible there are subtle symptoms I've been experiencing for so long they don't even register as problems at this point, and I might feel better if my sodium were higher.)

I know low sodium is dangerous in theory, but in my case, decades of experiencing it has not shown it to produce any of the classic or dangerous symptoms of hyponatremia you read about. Now, I'd still like to know what's causing it -- which could just be excessive water intake -- but I do sort of wonder at times why it's a problem at all just because of a specific number on a test.