Usually water toxicity is due to the body’s intake of water greatly exceeds the amount of water excreted, which leads to water retention in the body, thus causing a decrease in plasma osmolality and a sudden increase in circulating blood volume, the etiology of the following major points: First, increased water intake, because the body at once or a large intake of excessive water, for example, patients with chronic neurological disease appear primary excessive drinking, or suddenly too much infusion, too much intravenous rehydration Or oxytocin, posterior pituitary hormone application of excessive water intake can lead to excessive water intake. Secondly, renal dysfunction, excessive water intake can occur in the oliguric and anuric phases of acute renal failure, resulting in secondary water intoxication. Thirdly, excessive secretion of antidiuretic hormone, when the disease of excessive secretion of antidiuretic hormone such as massive bleeding, shock and acute infection, then there will be an imbalance in the secretion of antidiuretic hormone in the body and lead to water intoxication.