What is Hyponatremia?

Hyponatremia is a medical term indicating a low level of sodium (Na), and therefore usually salt, in the blood.

Severe or rapidly progressing hyponatremia can result in swelling of the brain (cerebral edema), and the symptoms of hyponatremia are mainly neurological. Hyponatremia is most often a complication of other medical illnesses in which either fluids rich in sodium are lost (for example because of diarrhea or vomiting), or excess water accumulates in the body at a higher rate than it can be excreted (for example in polydipsia or syndrome of inappropriate antidiuretic hormone).