Sodium:Themajorpositive ion (cation)inthe fluid surrounding cells in the body. The chemical notation forsodiumis Na+. When sodium is combined withchloride, the resultingsubstanceis a crystal calledtablesalt. Excess dietary sodium is largely excreted in the尿液, but too much salt in the diet tends to increase theblood pressure. Too much or too little sodium in theblood(called高钠血or hyponatremia respectively) can cause cells to malfunction, and extremes can be fatal. Normal blood sodium level is 135'145 milliEquivalents/liter(mEq/L) or 135'145 millimoles/liter (mmol/L) in international units.
