According to my drug handbook, normal sodium levels in the blood are between 130 and 150 milli-equivalents per liter. This is not the same as intake by any means. (*is sure that the biochem people will weigh in here.*) Hyponatremia can result in cramping, nausea, muscle weakness, increased heart rate and dangerously low blood pressure, among other things.
That's the closest thing I was able to find to 140 anything and a healthy sodium level.