Life is possible with water, even every CELL in the body needs water to live, but it’s possible to get too much or too little of the liquid, and that can cause some quite serious problems. The body’s liquid balance is not only affected by water that’s taken in by consuming food and drinks released in urine and sweat, but also by the concentration of sodium, an electrolyte.
Electrolytes are minerals that carry an electrical charge when dissolved in a liquid such as blood. In the body, sodium is mainly found in the fluid outside of cells and plays an important role in the movement of water into and out of them. Two different conditions, known as hyponatremia and hypernatremia, may result from changes in the balance of water in the body and levels of sodium in the blood.
Hyponatremia and hypernatremia are primarily disorders of water metabolism, said Dr. David Mount, a kidney specialist and clinical chief of the renal division at Brigham and Women’s Hospital in Boston. In hyponatremia, an excess of water in the body can lead to a low concentration of sodium in the blood, he said. And in hypernatremia, a deficit of water in the body can lead to a high concentration of sodium in the blood.
Hyponatremia is a low concentration of sodium in the blood because of an excessive retention of water, Mount said. In this electrolyte abnormality, there is too much water in the body and this dilutes sodium levels in the bloodstream, he noted. Hyponatremia occurs when blood sodium goes below normal levels, which is 135 mill equivalents/liter (mEq/L).
When sodium levels in the blood are too low, extra water goes into body cells causing them to swell. This swelling can be especially dangerous forebrain cells, resulting in neurological symptoms such as headache, confusion, irritability, seizures or even coma.
The symptoms of hyponatremia may be more serious when blood sodium lev-els drop very quickly and may be milder when they dip gradually, as those al-lows the body more time to adjust to the change. Other symptoms of the disorder include muscle cramps or weakness, nausea, vomiting, tiredness and a lack of energy.
In hypernatremia, the body contains too little water relative to the amount of sodium, Mount said. This causes sodium levels to become abnormally high in the blood — more than 145 mEq/L — which causes water to move out of body tissues and into the blood in an attempt to equalize the concentration between the two. Water can be lost from brain cells, causing them to shrink, which can be dangerous.