Water intoxication

Legend By Legend, 3rd Nov 2013 | Follow this author | RSS Feed
Posted in Wikinut>Health>General Health>Diseases & Infections

It is possible to cause significant damage to a person and even cause death if excess free water is consumed. This is called water intoxication and can be caused by a number of mechanisms.

Water and salt balance

Our bodies are generally constructed to consume a certain amount of salts while imbibing a certain amount of water. Our bodies can tolerate a fairly large range of amounts thanks to our kidneys which can concentrate and dilute our urine in response to our inidividual requirements. The goal of the kidneys is to maintain a constant blood volume and perfusion of organs while maintaining an appropriate concentration of solutes within the blood. The primary solutes concerned are sodium and potassium.

Water intoxication

Water intoxication occurs whenever more free water is imbibed than the body's ability to clear. The kidenys are limited by the rate at which they filter blood to generate urine and by their capability to dilute urine. Even the most dilute urine of the most capable kidneys still involves a certain amount of excretion of solutes. The result is a decrease in blood salts which can lead to serious consequences. Symptomatic water intoxication can present as confusion, instability of gait, seizures, coma and ,in severe cases, death.

Causes of water intoxication

Excess consupmtion of free water can be acheived by a number of ways. Some people drink excess water for psychiatric reasons (known as psychogenic polydipsia), others because they believe that drinking lots of water is healthy. People receiving their nuitrition via a nasogastric tube can be given excess fluids. Similarly, infants who have no control over what gets put in their bottle, are sometimes given excess free water. Given their reduced body weight and limited kidney capacity they are potentially very sensitive to excess water. Another possibilty is during prolonged sport or physical exertion. In this case, the person looses fluids and salts via his perspiration and if the person is supplemented with water but not other solutes and nuitrients a severe water intoxication can ensue. Certain medications can also make a person more prone to innapropriately concentrating urine which can eventually lead to water intoxication.

Correction of water intoxication

Given time and paitence, the kidneys will generally resolve the problem themselves, provided adequate solutes are administered and free water consumption is reduced. The problem is two fold. First - the situation that caused the water intoxication is unlikely to be reversed if the person is not symptomatic. Second - that if a person has already become symptomatic he requires a far more rapid correction than the kidneys can achieve on their own. In addition, if the person has an underlying condition which causes the kidney to needlessly concentrate urine and retain free water, correction of the water intoxication will be achieved without intervention (such as SIADH - syndrome of innapropriate ADH secretion - to be discussed in another article).

Treatment of water intoxication

Treatment of water intoxication generally involves water restriction as a first line. This should be enough for mild cases. In more severe cases, diuretics need to be administered. Another medication type that can be used are medication which block the vasopressin receptor. These are especially relevent when the person has an underlying problem of urine concentration such as described at the end of the previous paragraph.

Treatment risks - CPM

Correction of the salt disorder, although at times life saving, can be dangerous in itself. Overly rapid correction can result is massive shifts of fluid within the cells of the body. In particular, rapid correction of salt concentration can cause damage to neurons in the brain. Classically, this presents as CPM - Central Pontine Myelinosis. A neurological syndrome characterized by problems swallowing and speaking. More severe cases can result in varying degrees of paralysis. For this reason, any undertaking to correct water intoxication is done with caution and constant monitoring.

Tags

Central Pontine Myelinosis, Coma, Cpm, Free Water, Polydipsia, Seizure, Sodium, Water Intoxication

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author avatar Legend
I am a practicing physician. I have spent 5 years in Yeshiva studying religion. I published a card game on wikinut and I am in a process of getting divorced

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