Body fluids contain electrolytes (particularly sodium compounds, such as sodium chloride) in concentrations that must be held within very narrow limits. Water enters the body orally or intravenously and leaves the body primarily in urine, sweat, and exhaled water vapor. If water enters the body more quickly than it can be removed, body fluids are diluted and a potentially dangerous shift in electrolyte balance occurs.
Most water intoxication is caused by hyponatremia, an overdilution of sodium in the blood plasma, which in turn causes an osmotic shift of water from extracellular fluid (outside of cells) to intracellular fluid (within cells). The cells swell as a result of changes in osmotic pressure and may cease to function. When this occurs in the cells of the central nervous system and brain, water intoxication is the result. Additionally, many other cells in the body may undergo cytolysis, wherein cell membranes that are unable to stand abnormal osmotic pressures rupture, killing the cells. Initial symptoms typically include light-headedness, sometimes accompanied by nausea, vomiting, headache and/or malaise. Plasma sodium levels below 100 mmol/L (2.3g/L) frequently result in cerebral edema, seizures, coma, and death within a few hours of drinking the excess water. As with alcohol poisoning, the progression from mild to severe symptoms may occur rapidly as the water continues to enter the body from the intestines or intravenously.
A person with two healthy kidneys can excrete about 900ml (0.24 gal)/hr. Consuming as little as 1.8 litres of water (0.48 gal) in a single sitting may prove fatal for a person adhering to a low-sodium diet, or 3 litres (0.79 gallons) for a person on a normal diet. However, this must be modulated by potential water losses via other routes. For example, a person who is perspiring heavily may lose 1 L/hr (0.26 gal) of water through perspiration alone, thereby raising the threshold for water intoxication. The problem is further complicated by the amount of electrolytes lost in urine or sweat, which is variable within a range controlled by the body's regulatory mechanisms.
Water intoxication can be prevented by consuming water that is isotonic with water losses, but the exact concentration of electrolytes required is difficult to determine and fluctuates over time, and the greater the time period involved, the smaller the disparity that may suffice to produce electrolyte imbalance and water intoxication.
Sodium is not the only mineral that can become overdiluted from excessive water intake. Magnesium is also excreted in urine. According to the National Institutes of Health, "magnesium deficiency can cause metabolic changes that may contribute to heart attacks and strokes." Intravenous magnesium is used in cardiac care units for cardiac arrhythmias.
Prevention of water intoxication
Water intoxication can be prevented if a person's intake of water and electrolytes closely matches his or her losses. The body's regulatory mechanisms provide a very generous margin of safety if the two are imbalanced, but some extreme activities (such as heavy, prolonged physical exertion), as well as disease states, can overwhelm or impair these mechanisms. Avoid situations that provoke extreme or prolonged perspiration. Drinking fluids that are specially balanced to replace lost electrolytes can also help to prevent intoxication. Eating regularly can provide needed electrolytes if only normal water is available for rehydration.
Sports drinks are popular among athletes because they provide the necessary electrolytes to support extended exercise. They help keep the body balanced and carrying the right amount of fluids. However, not all drinks advertised as sports drinks are suitable for this purpose, and professional advice should be sought for potentially risky situations such as those described above.
Note that a person's innate sense of thirst is more sensitive to overall dehydration than to changes in electrolytes. Thus, it is possible to develop water intoxication while trying to satisfy thirst, if one drinks a great deal of water over a short period. A dangerous drop in electrolytes, such as the hyponatremia that leads to water intoxication, will not have any effect on thirst if one is sufficiently dehydrated.
For people suffering from dehydration due to the heavy perspiration associated with heavy exertion or heat stress, drinking water to rehydrate is much more important than avoiding water intoxication, since the former is extremely common and the latter is rare. One should never avoid drinking water under such conditions; instead, other steps should be taken to ensure that electrolytes are replaced as well, as noted above.
Notorious case of water intoxication
On January 12, 2007, Jennifer Strange, a 28-year-old woman and a mother of 3, from Rancho Cordova, California, was found dead in her home by her mother hours after trying to win a Nintendo Wii game console in KDND 107.9 "The End" radio station's "Hold Your Wee for a Wii" contest, which involved drinking large quantities of water without urinating. Ten radio station staff involved in the contest were later fired. The radio station is also now being sued by the family, and police are investigating for possible criminal charges.
24 Nisan 2017 Pazartesi
WATER INTOXICATION
Question: Can You Drink Too Much Water?
Answer: You've probably heard that it's important to 'drink plenty of fluids' or simply 'drink lots of water'. There are excellent reasons for drinking water, but have you ever wondered if it's possible to drink too much water. Here's what you need to know:
Can You Really Drink Too Much Water?
In a word, yes. Drinking too much water can lead to a condition known as water intoxication and to a related problem resulting from the dilution of sodium in the body, hyponatremia. Water intoxication is most commonly seen in infants under six months of age and sometimes in athletes. A baby can get water intoxication as a result of drinking several bottles of water a day or from drinking infant formula that has been diluted too much. Athletes can also suffer from water intoxication. Athletes sweat heavily, losing both water and electrolytes. Water intoxication and hyponatremia result when a dehydrated person drinks too much water without the accompanying electrolytes.
What Happens During Water Intoxication?
When too much water enters the body's cells, the tissues swell with the excess fluid. Your cells maintain a specific concentration gradient, so excess water outside the cells (the serum) draws sodium from within the cells out into the serum in an attempt to re-establish the necessary concentration. As more water accumulates, the serum sodium concentration drops -- a condition known as hyponatremia. The other way cells try to regain the electrolyte balance is for water outside the cells to rush into the cells via osmosis. The movement of water across a semipermeable membrane from higher to lower concentration is called osmosis. Although electrolytes are more concentrated inside the cells than outside, the water outside the cells is 'more concentrated' or 'less dilute' since it contains fewer electrolytes. Both electrolytes and water move across the cell membrane in an effort to balance concentration. Theoretically, cells could swell to the point of bursting.
From the cell's point of view, water intoxication produces the same effects as would result from drowning in fresh water. Electrolyte imbalance and tissue swelling can cause an irregular heartbeat, allow fluid to enter the lungs, and may cause fluttering eyelids. Swelling puts pressure on the brain and nerves, which can cause behaviors resembling alcohol intoxication. Swelling of brain tissues can cause seizures, coma and ultimately death unless water intake is restricted and a hypertonic saline (salt) solution is administered. If treatment is given before tissue swelling causes too much cellular damage, then a complete recovery can be expected within a few days.
It's Not How Much You Drink, It's How Fast You Drink It!
The kidneys of a healthy adult can process fifteen liters of water a day! You are unlikely to suffer from water intoxication, even if you drink a lot of water, as long as you drink over time as opposed to intaking an enormous volume at one time. As a general guideline, most adults need about three quarts of fluid each day. Much of that water comes from food, so 8-12 eight ounce glasses a day is a common recommended intake. You may need more water if the weather is very warm or very dry, if you are exercising, or if you are taking certain medications. The bottom line is this: it's possible to drink too much water, but unless you are running a marathon or an infant, water intoxication is a very uncommon condition.
Answer: You've probably heard that it's important to 'drink plenty of fluids' or simply 'drink lots of water'. There are excellent reasons for drinking water, but have you ever wondered if it's possible to drink too much water. Here's what you need to know:
Can You Really Drink Too Much Water?
In a word, yes. Drinking too much water can lead to a condition known as water intoxication and to a related problem resulting from the dilution of sodium in the body, hyponatremia. Water intoxication is most commonly seen in infants under six months of age and sometimes in athletes. A baby can get water intoxication as a result of drinking several bottles of water a day or from drinking infant formula that has been diluted too much. Athletes can also suffer from water intoxication. Athletes sweat heavily, losing both water and electrolytes. Water intoxication and hyponatremia result when a dehydrated person drinks too much water without the accompanying electrolytes.
What Happens During Water Intoxication?
When too much water enters the body's cells, the tissues swell with the excess fluid. Your cells maintain a specific concentration gradient, so excess water outside the cells (the serum) draws sodium from within the cells out into the serum in an attempt to re-establish the necessary concentration. As more water accumulates, the serum sodium concentration drops -- a condition known as hyponatremia. The other way cells try to regain the electrolyte balance is for water outside the cells to rush into the cells via osmosis. The movement of water across a semipermeable membrane from higher to lower concentration is called osmosis. Although electrolytes are more concentrated inside the cells than outside, the water outside the cells is 'more concentrated' or 'less dilute' since it contains fewer electrolytes. Both electrolytes and water move across the cell membrane in an effort to balance concentration. Theoretically, cells could swell to the point of bursting.
From the cell's point of view, water intoxication produces the same effects as would result from drowning in fresh water. Electrolyte imbalance and tissue swelling can cause an irregular heartbeat, allow fluid to enter the lungs, and may cause fluttering eyelids. Swelling puts pressure on the brain and nerves, which can cause behaviors resembling alcohol intoxication. Swelling of brain tissues can cause seizures, coma and ultimately death unless water intake is restricted and a hypertonic saline (salt) solution is administered. If treatment is given before tissue swelling causes too much cellular damage, then a complete recovery can be expected within a few days.
It's Not How Much You Drink, It's How Fast You Drink It!
The kidneys of a healthy adult can process fifteen liters of water a day! You are unlikely to suffer from water intoxication, even if you drink a lot of water, as long as you drink over time as opposed to intaking an enormous volume at one time. As a general guideline, most adults need about three quarts of fluid each day. Much of that water comes from food, so 8-12 eight ounce glasses a day is a common recommended intake. You may need more water if the weather is very warm or very dry, if you are exercising, or if you are taking certain medications. The bottom line is this: it's possible to drink too much water, but unless you are running a marathon or an infant, water intoxication is a very uncommon condition.
23 Nisan 2017 Pazar
Can You Drink Too Much Water?
But can there be too much of a good thing? In rare cases, drinking an extreme amount in a short time can be dangerous. It can cause the level of salt, or sodium, in your blood to drop too low. That's a condition called hyponatremia.It's very serious, and can be fatal. You may hear it called water intoxication.
How much would you have to drink? An enormous amount. Gallons and gallons of water.
"These are very isolated cases, and this is extremely rare," says Sharon Bergquist, MD. She's an assistant professor of medicine at Emory University School of Medicine in Atlanta. "More people by far and away are dehydrated, [rather] than having a problem with over-hydration."
What Is Water Intoxication?
If you drink a bottle of water here and there when you exercise or when you're hot, you’ll be fine. Where you run into problems is drinking way too much too fast.
"Young, healthy people don’t normally [get hyponatremia] unless they drink liters and liters of water at once, because your kidneys can only [expel] about half a liter at most an hour," says Chris McStay, MD. He's an emergency medicine doctor at the University of Colorado School of Medicine. "You're drinking more than your kidneys can pee out."
Causes
The issue boils down to sodium levels. One of sodium’s jobs is to balance the fluids in and around your cells. Drinking too much water causes an imbalance, and the liquid moves from your blood to inside your cells, making them swell. Swelling inside the brain is serious and requires immediate treatment.
Sometimes babies can have issues. Their bodies are so tiny that they can't handle lots of water. That's why doctors say infants should drink only milk or formula.
Then there are the cases like hazing rituals and publicized contests where people drink large amounts on purpose.
Symptoms and Treatment
The warning signs of hyponatremia look a lot like the symptoms of heatstroke and exhaustion. You might be hot, have a headache, and just feel crummy. Other early symptoms can include diarrhea, nausea, and vomiting.
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