Water intoxication can be fatal

With emphasis on increased water intake during exercise for the prevention of dehydration and exertional heat illness, there has been an increase in cases of water intoxication (a condition related to excessive water intake) in the US military. This study reviews several recent cases and three deaths amongst US military recruits that have occurred as a result of overhydration by drinking too water. Traditionally, emphasis was laid on the risk of not drinking enough water and the dangers associated with exertional heat illness (heat stroke), which has killed a number of healthy, young people. However, pushing the need to drink water too far can also have deadly consequences. All the cases of water intoxication were associated with more than 5 L (usually 10-20 Litres) of water intake during a period of a few hours. A 19-year-old Air Force recruit collapsed during a long walk, with a body temperature of 108 degrees F. Doctors concluded he had died of both heat stroke and low blood sodium levels as a result of overhydration. A 20-year-old trainee in the Army drank too much water during a 2 to 4 hour period while trying to produce a urine specimen for a drug test. She then became confused, lost consciousness, then died from swelling in the brain and lungs as a result of low blood sodium. Another 19-year-old navy recruit died from drinking too much water after a 26-mile march. Although he appeared fine during the beginning stages of the 8-hour walk, towards the end he began vomiting and was very tired. He was then sent to the hospital, where he went into a coma, developed brain swelling and died the next day. It is unclear how much water he drank during the walk, but he was given strong instructions on drinking water before and during the activity. Drinking too much water is dangerous because the body cannot excrete all the fluid rapidly. Excess water then goes to the bowel from where it is absorbed into the blood. Since the sodium concentration in the blood is lowered; it pulls sodium from the tissues, diluting the concentration of sodium in the tissues also. Changing concentrations of sodium, in turn, cause a shifting of fluids within the body, which can then induce a swelling in the brain. The swollen organ presses against the bones of the skull leading to brain damage. Previous cases of water toxicity have been noted in athletes who had consumed excessive amounts in order to avoid heat stroke. In addition, certain psychiatric patients may also drink too much water. The importance of maintaining adequate hydration in heat stroke prevention cannot be overemphasized, but excessive fluid intake may also prove life threatening. Current guidelines provide safety by limiting fluid intake during times of heavy sweating to 1 to 1.5 L per hour.