Overhydration, also called water excess or water intoxication, is a conditionin which the body contains too much water. It occurs when the body takes inmore water than it excretes, and its normal sodium level is diluted. This canresult in digestive problems, behavioral changes, brain damage, seizures, orcoma. An adult whose heart, kidneys, and pituitary gland are functioning properly would have to drink more than two gallons of water a day to develop water intoxication. The condition is most common in patients whose kidney function is impaired and may occur when health care professionals administer greater amounts of water-producing fluids and medications than the patient's body can handle.

Infants are especially likely to develop overhydration. The Centers for Disease Control and Prevention has cautioned that babies are particularly susceptible to the problem during the first month of life, when the kidneys' filtering mechanism is too immature to excrete fluid as rapidly as older infants do. Breast milk or formula provide all the fluids a healthy baby needs. Water should be given slowly, sparingly, and only during extremely hot weather.

For adults, drinking too much water rarely causes overhydration when the body's systems are working normally. People with heart, kidney, or liver diseaseare more likely to develop overhydration because their kidneys are unable toexcrete water normally. It may be necessary for people with these disorders to restrict the amount of water they drink and/or adjust the amount of salt intheir diets.

Overhydration can cause acidosis (a condition in which blood and body tissueshave an abnormally high acid content), anemia, cyanosis (a condition that occurs when oxygen levels in the blood drop sharply), hemorrhage, and shock. The brain is the organ most vulnerable to the effects of overhydration. If excess fluid levels accumulate gradually, the brain may be able to adapt to themand the patient will have only a few symptoms. If the condition develops rapidly, confusion, seizures, and coma are likely to occur.

Since the brain particularly susceptible, behavior changes are the usually the first symptoms of water intoxication. The patient may become confused, drowsy, or inattentive. Shouting and delirium are common. Other symptoms of overhydration may include blurred vision, muscle cramps and twitching, paralysis on one side of the body, poor coordination, nausea and vomiting, rapid breathing, sudden weight gain, and weakness. Blood pressure is sometimes, but not always higher than normal.

Chronic illness, malnutrition, a tendency to retain water, and kidney diseases and disorders increase the likelihood of becoming overhydrated. Infants andthe elderly are at increased risk for overhydration, as are people with certain mental disorders or

Before treatment can begin, a doctor must determine whether a patient's symptoms are due to overhydration, in which excess water is found inside and outside cells, or excess blood volume, in which high sodium levels prevent the body from storing excess water inside the cells.

Mild overhydration can generally be corrected by following a doctor's instructions to limit fluid intake. In more serious cases, diuretics may be prescribed to increase urination, although these drugs tend to be most effective in the treatment of excess blood volume. Identifying and treating any underlyingcondition (such as impaired heart or kidney function) is crucial.

In patients with severe symptoms, fluid imbalances must be corrected immediately. A powerful diuretic and fluids to restore normal sodium concentrations are given rapidly at first. When the patient has absorbed 50% of these substances, blood levels are measured. Treatment then continues at a more moderate pace in order to prevent brain damage that could occur from sudden changes inblood chemistry.

Untreated water intoxication can be fatal, but this outcome is quite rare.

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