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I came across this article for Gabe Mirkin's e-zine and I thought it interesting:

Hyponatremia - too much waterGabe Mirkin, M.D.

For the last 40 years, sports medicine experts have told athletes in endurance events that they should take fluids frequently during events lasting more than one hour. However, three years ago, a 28-year-old woman collapsed and died after finishing the Boston Marathon. Her blood salt levels were extremely low and she died from a condition called hyponatremia. A few weeks ago, a policeman training for bicycle duty died of the same condition. On July 26, 2005, sports medicine experts issued a warning to all athletes from the First International Exercise-Associated Hyponatremia Consensus Development Conference.

I have never seen this syndrome in well-conditioned athletes. It has been reported almost exclusively in very thin, less-fit, slower and novice athletes, and is far more common in women. This condition is caused by drinking too much fluid and is not caused by excessive loss of salt in sweat or by exercising. When people with psychiatric problems force themselves to drink huge amounts of water while sitting still, they also can die of hyponatremia, only in this case, it is called water intoxication.

The extra fluid expands blood volume and dilutes blood salt levels. This causes blood salt levels to be very low, while brain salt levels remain normal. Fluid moves from an area of low salt concentration into areas with high salt levels. So fluid moves from the bloodstream into the brain, causing brain swelling. Since the brain is enclosed in the skull, which is a tight box, the brain expands and has nowhere to go, so it is squashed to cause headache, nausea, and blurred vision. Since these are the same symptoms caused by pure dehydration with normal blood salt levels, the only way to diagnose the condition is with blood tests. As blood salt levels drop even lower, the person becomes confused, develops seizures and falls unconscious. You should suspect hyponatremia when the event takes more than four hours, the athlete is a thin woman in her first ultra-long endurance event, and when she has been drinking heavily as she exercises. All people who are confused, pass out or have seizures should be sent to a hospital immediately. The condition requires skilled management because the first impulse of an inexperienced physician is to give intravenous fluids, which dilute blood salt levels further and swell the brain and can kill the patient.

How much fluid should you drink? You will not become thirsty during exercise until you have lost between two and four pints of fluid, so you can't wait for thirst to encourage you to drink. Dehydration makes you tired and it is unlikely that you can replace the lost fluid during a race after you have become thirsty. Blood has a much higher concentration of salt than sweat, so when you sweat, you lose far more water than salt. This causes blood salt levels to rise. Thirst is controlled by certain cells in your brain called osmoreceptors which are stimulated to make you thirsty only after blood salt levels have risen considerably. So you will not become thirsty until you are significantly dehydrated.

The American College of Sports Medicine recommends a limit of 1200cc (5 cups, 2.5 pints, a little over 1 quart, or 2 average size water bottles) per hour, but for a person who is not exercising near his or her maximum, this could be too much. A person exercising near his capacity and not slowed down by fatigue probably does not have to worry about limiting fluid intake. He is working so hard at maintaining intensity, he doesn't have enough time to drink too much. On the other hand, people slowed down by fatigue or those out of shape, should limit fluid intake, probably to less than two large water bottles per hour. If you are exercising for more than an hour, you should also replace salt, either with salted sports drinks or salted foods.

Clinical Journal of Sport Medicine, July/August 2005

Reported August 21, 2005

Web www.DrMirkin.com

To receive Dr. Mirkin's free health & fitness E-Zine each week, send a blank email to subscribe@drmirkin.com

Dr. Mirkin's opinions and the references cited are for information only, and are not intended to diagnose or prescribe. For your specific diagnosis and treatment, consult your doctor or health care provider.

Copyright 2006 www.DrMirkin.com

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I discovered that whole salt/fluid ratio when I would start to get symptoms, and the first thing I would do is get a cold drink of water...which actually made things worse. I started drinking Gatorade when I could not eat anything, and found I didn't get symptoms as bad. Salt, who would have guessed?

I usually drink a bottle of gatorade a day. Once I'm done, I fill it halfway with water, and drink that the rest of the night. Works like a charm. Even with all the excessive heat, I haven't had any symptoms.

Oh yea, not only does your brain swell in that hypoatremia condition, but I've read so does your other organs (liver, kidneys, etc.). They basically get 'diluted' with so much water, they cannot function. Truly amazing.

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very interesting--thanks. I know during pregnancy I would have episodes when I would be so so thirsty and I would drink A LOT of water. (I didn't have a diagnosis of POTS then.) I had no understanding that there was a possibibility one could actually drink too much. Thanks for the warning for everyone.

Katherine

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I have hyponatremia on and off but not caused by an excessive intake of fluids.

A simple urine test that measures the electrolytes in your urine will tell you if you are drinking too much and flushing the salt out. :angry:

After recently going through a drastic drop in electrolytes, I had one doctor tell me I drink too much fluids and to cut back. This caused dehydration! Finally, another doctor measured the electrolytes in my urine which was nil and told me to go ahead and drink as much as I need too.

Hope this helps :P

Maggs

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I have found that drinking too much water actually makes my NCS episodes worse (just like not having enough). I use to take a gallon of water with me and try to drink most of it (with salty foods) before trying the drugs for ncs, but this aggravated my condition.

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Too much plain water makes MANY of us worse. Especially those of us low on the ADH hormone who benefitted from DDAVP. After years of drinking and flushing everything right back out. cardiologist and my ANS doc say to drink more Gatorade..and when weak, add a pinch of salt to that.

Water makes me much worse...Diluted gatorade and salty snacks are needed in this weather for sure for my situation. Without DDAVP I PEED myself into dehydration but that has been rehashed here many times.

Too hot for me to repeat. Feels like 96 at 9pm and DEWPOINT is 78!!! YIKES!

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This has happened to me twice- though not so extreem as the examples given. I am limited to a strict 3 ltrs per day even though I am pregnant. Last summer when suffering badly with pots I drank lots of water as I thought that it was helping but it was all in my head. I was actually damaging my kidneys. Its great that you have brought this to everyones attention. I hope no one else here suffers this summer!

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i have heard this before...it is true! in school they taught us that "salt follows water" so you can get an electrolyte imbalance if you drink too much water. ...but i just wanted to mention for those that have the hyperadrenergic form of POTS that it's important to be careful of getting too much salt (according to dr. grubb) because it can raise your blood pressure even more......

but, even with that said, i would venture to guess that everyone is different; i have been battling this fluid imbalance for some time now. i've consistently drunk lots and lots of water, just as dr. grubb recommended, and have still run into BIG problems w/ POTS symptoms and NCS symptoms. i've tried combinations of water and gatorade, varieties of beverages, stopped caffeine...the dehydration/fluid imbalance issue seems it will remain a mystery for me. no one can explain why my body behaves this way.

i was tested for diabetes, diabetes insipidus and other fluid/electrolyte imbalance stuff and everything was normal. but every once in awhile i still have to go get IV saline, whether i'm drinking 4 litres or 2, straight water or gatorade or combo. this winter i went every 48 hours for IV therapy and this summer, when you would think i'd have dehydration issues, i haven't needed it yet! definitely strange. i've just chalked it up to some as-yet-unknown dysautonomia related issue. or perhaps i actually AM an alien? LOL

anyone else deal with such craziness?

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