Hyponatremia:Water Intoxication

Water makes about 60 percent of the human body, runs through the blood and inhabits the cells. Water escapes the body through sweat, urination, exhaled breath, among other routes. Replacing these lost stores is essential but rehydration can be overdone. There is such a thing as a fatal water overdose.

Earlier this year, a 28-year-old California woman died after competing in a radio station’s on-air water-drinking contest. After downing some six liters of water in three hours in the “Hold Your Wee for a Wii” contest, Jennifer Strange vomited, went home with a splitting Headaches, and died from so-called water intoxication.

HYPONATREMIA:

It means “insufficient salt in the blood.” It means having a blood sodium concentration below 135 millimoles per liter. Severe cases of hyponatremia can lead to water intoxication. Water intoxication symptoms include headache, fatigue, nausea, vomiting, frequent urination and mental disorientation.

Most cells have room to stretch because they are embedded in flexible tissues such as fat and muscle, but this is not the case for neurons. Brain cells are tightly packaged inside a rigid boney cage, the skull, and they have to share this space with blood and cerebrospinal fluid. Inside the skull there is almost zero room to expand and swell.

Thus, brain edema, or swelling, can be disastrous. “Rapid and severe hyponatremia causes entry of water into brain cells leading to brain swelling, which manifests as seizures, coma, respiratory arrest, brain stem herniation and death. ”

VASOPRESSIN:

Most cases of water poisoning do not result from simply drinking too much water. It is usually a combination of excessive fluid intake and increased secretion of vasopressin(also called antidiuretic hormone). Produced by the hypothalamus and secreted into the bloodstream by the posterior pituitary gland, vasopressin instructs the kidneys to conserve water. Its secretion increases in periods of physical stress during a marathon.

A healthy kidney at rest can excrete 800 to 1,000 milliliters of water without experiencing a net gain in water per hour.

While exercising, “you should balance what you’re drinking with what you’re sweating”. That includes sports drinks, which can also cause hyponatremia when consumed in excess. “If you’re sweating 500 milliliters per hour, that is what you should be drinking.”