Water Intoxication

Water intoxication
Other names: Water poisoning,[1] hypotonic hyperhydration,[1] overhydration, water toxicity,[2] water toxemia
Specialty	Toxicology, critical care medicine
Symptoms	Large amounts of urine, headache, weakness, muscle cramps, nausea, confusion[1]
Complications	Seizures, osmotic demyelination syndrome[1]
Causes	Drinking excess water[1]
Risk factors	Psychiatric conditions, child abuse, ecstasy, water-drinking contests, excess fluids during exercise[1][3]
Prevention	Drinking to thirst during sport, oral rehydration solutions[4]
Medication	Restricting fluids, intravenous hypertonic saline[5][4]
Frequency	Rare[1]

Water intoxication (WI) is a condition that occurs due to drinking excessive amounts of water.^[1] Initial symptoms include production of large amounts of urine.^[1] More severe symptoms may include headache, weakness, muscle cramps, nausea, and confusion.^[1] Complications may include seizures and osmotic demyelination syndrome.^[1][5]

It can occur as a result of psychiatric conditions including schizophrenia and anorexia, child abuse, ecstasy use, water-drinking contests, or drinking excess fluids during exercise.^[1][3] Other causes include excessive intravenous sugar solution without sufficient salt and a method of torture in which a person is forced to drink excessive amounts of water.^[1] The underlying mechanism involves the introduction of more water than the kidneys can eliminate resulting in low blood sodium.^[1][4] As the blood becomes hypotonic the brain swells.^[1]

Prevention in sports is by drinking to match ones thirst.^[4] Using oral rehydration solutions rather than sports drinks may also help.^[4] For mild cases, restricting fluids may be sufficient.^[5] For severe cases intravenous hypertonic saline may be used.^[4] Water intoxication is rare.^[1] Death has occurred from drinking 6 liters of water over three hours.^[6] The condition has been described since at least 1923 by Rowntree.^[7][8]

Signs and symptoms[edit | edit source]

Initial symptoms include production of large amounts of urine.^[1] More severe symptoms may include headache, weakness, muscle cramps, nausea, and confusion.^[1] Increased intracranial pressure may result in a low heart rate and high blood pressure.^[2] Troubles with breathing may also occur.^[5]

Complications may include seizures and osmotic demyelination syndrome.^[1][5]

Risk factors[edit | edit source]

Psychiatry[edit | edit source]

Psychogenic polydipsia is a psychiatric condition in which people feel compelled to drink large quantities of water. This condition can be especially dangerous if the person also exhibits other psychiatric indications (as is often the case), as the care-takers might misinterpret the hyponatremic symptoms.^[9]

Exercise[edit | edit source]

Long distance runners are susceptible to water intoxication if they drink too much, resulting in sodium levels dropping below 135 mmol/L. It used to be encouraged to drink excessive fluids.^[10] During the 2002 Boston Marathon thirteen percent finished the race with hyponatremia. The strongest predictor of hyponatremia was weight gain while racing (over-hydration), and hyponatremia was just as likely to occur in runners who chose sports drinks as those who chose water.^[10]

Hyponatremia and other physical conditions associated with water intoxication are more often seen in those participating in military training. One US Army study found 17 trainees admitted to hospital over a year's period for water intoxication^[11] while another found that three soldiers had died, leading to a recommendation that no more than 1–1.5 L of water should be consumed per hour of heavy sweating.^[12]

Heat stress[edit | edit source]

Any activity or situation that promotes heavy sweating can lead to water intoxication when water is consumed to replace lost fluids. Persons working in extreme heat or humidity for long periods must take care to drink and eat in ways that help to maintain electrolyte balance. People using drugs such as MDMA (often referred to colloquially as "Ecstasy") may overexert themselves, perspire heavily, feel increased thirst, and then drink large amounts of water to rehydrate, leading to electrolyte imbalance and water intoxication – this is compounded by MDMA use increasing the levels of antidiuretic hormone (ADH), decreasing the amount of water lost through urination.^[13] Even people who are resting quietly in extreme heat or humidity may run the risk of water intoxication if they drink large amounts of water over short periods for rehydration.

Health care[edit | edit source]

Health care related cases have occurred due to gastric lavage as well as people drinking too much water with gastroenteritis.^[14]

When an unconscious person is being fed intravenously (for example, total parenteral nutrition) or via a nasogastric tube, the fluids given must be balanced in composition to match fluids and electrolytes lost. These fluids are typically hypertonic, and so water is often also given. If the electrolytes are not monitored, either hypernatremia or hyponatremia may result.^[15]

Some medications (oxcarbazepine, among others) have been found to cause hyponatremia in some.^[16] People with diabetes insipidus are particularly vulnerable due to rapid fluid processing.^[17]

Infants[edit | edit source]

It can be very easy for children under one year old (especially those under nine months) to absorb too much water. Because of their small body mass, it is easy for them to take in a large amount of water relative to body mass and total body sodium stores.^[18]

Pathophysiology[edit | edit source]

Water, just like any other substance, can be considered a poison when over-consumed. Water intoxication mostly occurs when water is being consumed in a high quantity without adequate electrolyte intake.^[19] Water is considered one of the least toxic chemical compounds, with an LD₅₀ exceeding 90 ml/kg in rats.^[20]

At the onset of this condition, fluid outside the cells has an excessively low amount of solutes, such as sodium and other electrolytes, in comparison to fluid inside the cells, causing the fluid to move into the cells to balance its osmotic concentration. This causes the cells to swell. The swelling increases intracranial pressure in the brain, which leads to the first observable symptoms of water intoxication: headache, personality changes, changes in behavior, confusion, irritability, and drowsiness. These are sometimes followed by difficulty breathing during exertion, muscle weakness and pain, twitching, or cramping, nausea, vomiting, thirst, and a dulled ability to perceive and interpret sensory information. As the condition persists, papillary and vital signs may result including bradycardia and widened pulse pressure. The cells in the brain may swell to the point where blood flow is interrupted resulting in cerebral edema. Swollen brain cells may also apply pressure to the brain stem causing central nervous system dysfunction. Both cerebral edema and interference with the central nervous system are dangerous and could result in seizures, brain damage, coma or death.^[21]

Prevention[edit | edit source]

Water intoxication can be prevented if a person's intake of water does not grossly exceed their losses. Healthy kidneys are able to excrete approximately 800 millilitres to one litre of fluid water (0.84–1.04 quarts) per hour.^[22] However, stress (from prolonged physical exertion), as well as disease states, can reduce this amount.^[22]

Treatment[edit | edit source]

For mild cases, restricting fluids may be sufficient.^[5] In more severe cases, treatment consists of intravenous hypertonic saline.^[4] 3% normal saline at a dose of 2 ml/kg, up to a maximum of 100 ml, may be given over 10 minutes.^[5] This may be repeated if symptoms have not resolved and the increase in blood sodium levels is less than 10 mEq/L.^[5] Correcting sodium levels to rapidly may result in osmotic demyelination syndrome.^[5]

Mannitol and vasopressin antagonists are not generally recommended.^[2]

Notable cases[edit | edit source]

• 1097: During the First Crusade, according to one chronicle, many crusaders died after drinking too much from a river while marching to Antioch.^[23]
• 1991, Andy Warhol: Five years after his death, Warhol's family publicly accused the hospital where he had his gallbladder removed of causing his death by water intoxication administered post-operatively. A claimed autopsy weight of 68 kg (150 lb), with his weight being 58 kg (128 lb) when admitted, was cited as evidence that too much fluid had been given.^[24]
• November 16, 1995: Leah Betts, a British schoolgirl, died as the result of drinking too much water, though in the media her death was mistakenly attributed to taking an ecstasy tablet at her 18th birthday party.^[25]
• 2003: British actor Anthony Andrews survived a case of water intoxication. He was performing as Henry Higgins in a revival of the musical My Fair Lady at the time, and consumed up to eight litres of water a day. He was unconscious and in intensive care for three days.^[26][27]
• February 2, 2005: Matthew Carrington, a student at Chico State University in Chico, California, died as a direct result of a fraternity hazing ritual involving forced water intoxication.
• January 12, 2007: Jennifer Strange died after drinking nearly 7.6 liters (2 gallons) of water in an attempt to win a Nintendo Wii.^[28] The KDND radio station's morning show, the Morning Rave, held an on-air contest entitled "Hold Your Wee for a Wii," in which contestants were asked to drink as much water as they could without urinating. The DJs were made aware of the dangers but did not inform the contestants. KDND's parent company, Entercom Sacramento LLC, was subsequently ordered to pay $16.5 million in damages to Strange's family.^[29][30]
• March 11, 2020: Zachary Sabin, an 11-year-old, died after being forced to drink almost three liters of water in just four hours by his parents. They thought his urine was too dark, so they made him drink water until he threw up.^[31]

See also[edit | edit source]

• Dihydrogen monoxide hoax
• List of unusual deaths
• Potomania

References[edit | edit source]

External links[edit | edit source]

Classification	ICD-10: E87.7 ICD-9-CM: 276.69 DiseasesDB: 29222