Hypernatremia: Elevated blood sodium.
Sodium is the major positive ion (cation) in fluid outside of
cells. The chemical notation for sodium is Na+ (from
natrium, a synonym for sodium). When combined with chloride (Cl), the
resulting substance is table salt (NaCl).
Excess sodium (such as from fast food hamburger and fries) is
excreted in the urine. Too much (or too little) sodium can cause
cells to malfunction, and extremes can be fatal.
The normal blood sodium level is 135 - 145 milliEquivalents/liter
(mEq/L), or in international units, 135 - 145 millimoles/liter