Main Page | See live article | Alphabetical index (Greek hypo- - under, below, lower; Latin [obsolete] natrium - sodium; Greek -haemia/ -aemia/ -hemia/ -emia - blood condition) Hyponatremia occurs when sodium in the blood is at a low level. Sodium ions (Na+) help to distribute fluids in your body. A lack of sodium can therefore cause dehydration. Water and salt are lost by sweating, and salt contains sodium. This article is a stub. You can help Wikipedia by fixing it. This article is from Wikipedia. All text is available under the terms of the GNU Free Documentation License.