Hyponatremia

Hyponatremia describes a low level of salt in the blood. It is most commonly caused by drinking too much water too quickly. However, it can also be caused by excessive sweating associated with intense exercise over lengthy periods of time, typical of a marathon.
Hyponatremia is usually accompanied by nausea, headache, confusion and lethargy with symptoms progressing as salt levels continue to fall. In extreme cases, it can lead to coma.
No matter what the cause, replacement of sodium is the typical treatment. However, this must be done in a controlled manner as raising levels too quickly can lead to complications.
Hyponatremia at Wikipedia
Category:Diseases