What causes hyponatremia (low blood sodium)?
A low sodium level in the blood may result from excess water or fluid in the body, diluting the normal amount of sodium so that the concentration appears low. This type of hyponatremia can be the result of chronic conditions such as kidney failure (when excess fluid cannot be efficiently excreted) and congestive heart failure, in which excess fluid accumulates in the body. SIADH (syndrome of inappropriate anti-diuretic hormone) is a disease whereby the body produces too much anti-diuretic hormone (ADH), resulting in retention of water in the body. Consuming excess water, for example during strenuous exercise, without adequate replacement of sodium, can also result in hyponatremia. Hyponatremia can also result when sodium is lost from the body or when both sodium and fluid are lost from the body, for example, during prolonged sweating and severe vomiting or diarrhea. Medical conditions that can sometimes be associated with hyponatremia are adrenal insufficiency, hypothyroidism, and cirr
