Water intoxication

Disease class: Water-electrolyte imbalance

Physiology

In healthy individuals, the kidneys and urinary tracts remove excessive water from the body to maintain an optimal blood pressure and plasma osmolality.
The kidneys employ several mechanisms to conserve the largest quantity of electrolyes possible when excreting large amounts of water.

 

Pathophysiology 

However, there is a limit to the rate of water excretion. Since water cannot be excreted without some loss of electrolytes, a large volume of water excreted results in a large derangement in electrolytes. It is possible, but uncomfortable to ingest water at a sufficient rate to overwhelm these systems.
The low osmolality may result in cerebral oedema, as water diffuses out of the blood (by osmosis) more easily.

 

Cause

• Extreme overconsumption of water (e.g. 7-8L in 24 hours) for any reason
• Overconsumption of water secondary to MDMA abuse

 

Management

• Fluid restriction
• Diuretics
• Vasopressin receptor antagonists