0 Members and 1 Guest are viewing this topic.
today i worked from nine to five. i had nothing to drink from nine to about two thirty. i was SO thirsty that i drank a whole bottle of water. about fifteen minutes later, i got sick and all the water came back out. it was rather unpleasant, and then i was thirsty again but afraid to drink anything. does anyone know why this happened?
The heat could also be making you sweat a lot, and this can cause loss of salt too - it is important in these conditions to make sure that you replenish both water and salt levels, otherwise you can get water poisoning (too dilute a blood, with insufficient salt).
I seem to remember hearing that a morning drink of water with "some" salt added was beneficial, not sure if this is true or why.
Quote from: another_someone on 10/07/2007 12:03:34The heat could also be making you sweat a lot, and this can cause loss of salt too - it is important in these conditions to make sure that you replenish both water and salt levels, otherwise you can get water poisoning (too dilute a blood, with insufficient salt).I seem to remember hearing that a morning drink of water with "some" salt added was beneficial, not sure if this is true or why.
from what i have gathered, that is the theory behind gatorade. i'm thinking i was dehydrated and just drank it way too fast for my body to understand what i was doing to it. it's hard to sip at something when you're so thirsty though!
Water intoxication (also known as hyperhydration or water poisoning) is a potentially fatal disturbance in brain function that results when the normal balance of electrolytes in the body is pushed outside of safe limits by a very rapid intake of water. Normal, healthy individuals have little to worry about accidentally overconsuming water. Nearly all deaths related to water intoxication in normal individuals have resulted either from water drinking contests, in which individuals attempt to consume several gallons over the course of just a few minutes, or long bouts of intensive exercise during which time electrolytes are not properly replenished, yet massive amounts of fluid are still consumedPhysiologyBlood contains 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 healthy kidneys can excrete about 900ml (0.24 gal)/hr. 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.[clarify] 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.High risk factorsLow body mass (infants)It can be very easy for children under a year old to absorb too much water – especially if the child is under nine months old, because with their small body mass, it is easy to take in a large amount of water relative to body mass. It is also possible for a child to absorb too much water if submerged in it.Endurance sportsMarathon runners are susceptible to water intoxication if they drink only water while running. Although sweat is relatively hypotonic compared with body fluids, marathon runners perspire heavily for long periods, potentially causing their sodium levels to drop when they consume large amounts of fluids to quench their thirst. The replacement fluids may not contain sufficient sodium to replace what has been lost, and this puts them at high risk for water intoxication. Medical personnel at marathon events are trained to immediately suspect water intoxication when runners collapse or show signs of confusion. Properly designed electrolyte-replacement drinks and some sports drinks include electrolytes that make them roughly isotonic with sweat, which helps to prevent water intoxication.Note that overconsumption of sodium (in drinks or also in food), as well as inadequate intake of water, can cause hypernatremia, a disorder that is nearly the opposite of water intoxication and equally dangerous. Improper use of salt tablets can cause hypernatremia also.Overexertion and heat stressAny 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 and/or humidity for long periods must take care to drink and eat in ways that help to maintain electrolyte balance. Persons using drugs such as MDMA ("Ecstasy") may overexert themselves, perspire heavily, and then drink large amounts of water to rehydrate, leading to electrolyte imbalance and water intoxication. 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.Psychiatric conditionsPsychogenic polydipsia is the psychiatric condition in which patients feel compelled to drink large quantities of water, thus putting them at risk of water intoxication. This condition can be especially dangerous if the patient also exhibits other psychiatric indications (as is often the case), as his or her care-takers might misinterpret the hyponatraemic symptoms.Drug useUsers of drugs, such as ecstasy are at risk. See the case of Leah Betts.Specific diseaseDiarrhea and vomiting can result in very large electrolyte losses, and although drinking water will replace lost water, the lost electrolytes may not be adequately replaced, which can result in water intoxication. Replacement fluids for vomiting and diarrhea should be properly balanced to make them isotonic with the fluids lost in these conditions. Special formulations exist for oral rehydration therapy in these cases.A great many disorders can affect electrolyte balance, especially disorders of the kidneys. Diuretic therapy, mineralocorticoid deficiency, osmotic diuresis (as in the hyperglycemia of uncontrolled diabetes), and the multiple disorders associated with AIDS are other common causes of electrolyte imbalance, although they do not always produce water intoxication.
Liquid H2O is the sine qua non of life. Making up about 66 percent of the human body, water runs through the blood, inhabits the cells, and lurks in the spaces between. At every moment water escapes the body through sweat, urination, defecation or exhaled breath, among other routes. Replacing these lost stores is essential but rehydration can be overdone. There is such a thing as a fatal water overdose.Earlier this year, a 28-year-old California woman died after competing in a radio station's on-air water-drinking contest. After downing some six liters of water in three hours in the "Hold Your Wee for a Wii" (Nintendo game console) contest, Jennifer Strange vomited, went home with a splitting headache, and died from so-called water intoxication.There are many other tragic examples of death by water. In 2005 a fraternity hazing at California State University, Chico, left a 21-year-old man dead after he was forced to drink excessive amounts of water between rounds of push-ups in a cold basement. Club-goers taking MDMA ("ecstasy") have died after consuming copious amounts of water trying to rehydrate following long nights of dancing and sweating. Going overboard in attempts to rehydrate is also common among endurance athletes. A 2005 study in the New England Journal of Medicine found that close to one sixth of marathon runners develop some degree of hyponatremia, or dilution of the blood caused by drinking too much water.Hyponatremia, a word cobbled together from Latin and Greek roots, translates as "insufficient salt in the blood." Quantitatively speaking, it means having a blood sodium concentration below 135 millimoles per liter, or approximately 0.4 ounces per gallon, the normal concentration lying somewhere between 135 and 145 millimoles per liter. Severe cases of hyponatremia can lead to water intoxication, an illness whose symptoms include headache, fatigue, nausea, vomiting, frequent urination and mental disorientation.In humans the kidneys control the amount of water, salts and other solutes leaving the body by sieving blood through their millions of twisted tubules. When a person drinks too much water in a short period of time, the kidneys cannot flush it out fast enough and the blood becomes waterlogged. Drawn to regions where the concentration of salt and other dissolved substances is higher, excess water leaves the blood and ultimately enters the cells, which swell like balloons to accommodate it. Most cells have room to stretch because they are embedded in flexible tissues such as fat and muscle, but this is not the case for neurons. Brain cells are tightly packaged inside a rigid boney cage, the skull, and they have to share this space with blood and cerebrospinal fluid, explains Wolfgang Liedtke, a clinical neuroscientist at Duke University Medical Center. "Inside the skull there is almost zero room to expand and swell," he says. Thus, brain edema, or swelling, can be disastrous. "Rapid and severe hyponatremia causes entry of water into brain cells leading to brain swelling, which manifests as seizures, coma, respiratory arrest, brain stem herniation and death," explains M. Amin Arnaout, chief of nephrology at Massachusetts General Hospital and Harvard Medical School.Where did people get the idea that guzzling enormous quantities of water is healthful? A few years ago Heinz Valtin, a kidney specialist from Dartmouth Medical School, decided to determine if the common advice to drink eight, eight-ounce glasses of water per day could hold up to scientific scrutiny. After scouring the peer-reviewed literature, Valtin concluded that no scientific studies support the "eight x eight" dictum (for healthy adults living in temperate climates and doing mild exercise). In fact, drinking this much or more "could be harmful, both in precipitating potentially dangerous hyponatremia and exposure to pollutants, and also in making many people feel guilty for not drinking enough," he wrote in his 2002 review for the American Journal of Physiology—Regulatory, Integrative and Comparative Physiology. And since he published his findings, Valtin says, "not a single scientific report published in a peer-reviewed publication has proven the contrary." Most cases of water poisoning do not result from simply drinking too much water, says Joseph Verbalis, chairman of medicine at Georgetown University Medical Center. It is usually a combination of excessive fluid intake and increased secretion of vasopression (also called antidiuretic hormone), he explains. Produced by the hypothalamus and secreted into the bloodstream by the posterior pituitary gland, vasopressin instructs the kidneys to conserve water. Its secretion increases in periods of physical stress—during a marathon, for example—and may cause the body to conserve water even if a person is drinking excessive quantities.Every hour, a healthy kidney at rest can excrete 800 to 1,000 milliliters, or 0.21 to 0.26 gallon, of water and therefore a person can drink water at a rate of 800 to 1,000 milliliters per hour without experiencing a net gain in water, Verbalis explains. If that same person is running a marathon, however, the stress of the situation will increase vasopressin levels, reducing the kidney's excretion capacity to as low as 100 milliliters per hour. Drinking 800 to 1,000 milliliters of water per hour under these conditions can potentially lead a net gain in water, even with considerable sweating, he says.While exercising, "you should balance what you're drinking with what you're sweating," and that includes sports drinks, which can also cause hyponatremia when consumed in excess, Verbalis advises. "If you're sweating 500 milliliters per hour, that is what you should be drinking."But measuring sweat output is not easy. How can a marathon runner, or any person, determine how much water to consume? As long as you are healthy and equipped with a thirst barometer unimpaired by old age or mind-altering drugs, follow Verbalis's advice, "drink to your thirst. It's the best indicator."