Hyponatremia

It is that time of year at the Grand Canyon. I found it interesting to follow up the linked wikipedia article on hyponatremia, especially when it mentions how common a condition it can be. My understanding is that one way HN occurs is when you ingest too much water, especially without electrolytes, which is difficult to do in the desert Southwest, typically because of the low humidity......


Grand Canyon National Park (AZ)
Ailing Hiker Rescued Via Helicopter Short-Haul

Late in the day on Tuesday, June 4th, visitors found a 29-year-old man in severe distress on the North Kaibab Trail. The hiker reportedly drank large amounts of water, but had eaten very little food. This, coupled with the expected increased perspiration while hiking in hot temperatures, lead rangers to believe this visitor was suffering from a potentially life-threatening condition due to low blood sodium levels known as hyponatremia. Responding via helicopter, ranger/medic Brian Bloom utilized a portable blood chemistry instrument (iStat) to confirm his suspicions and begin appropriate field treatment. Due to the serious nature of the man’s condition and the lack of nearby landing zones, he was helicopter short-hauled with Bloom from switchbacks in the Redwall to the North Rim helibase. He was then placed inside the helicopter, flown to the South Rim, and taken from there to Flagstaff Medical Center. Heis expected to recover.
[Submitted by Brandon Torres, Branch Chief of Emergency Services]

Hyponatremia was discussed at the WFR recert I recently attended. According to the instructor there have been more issues during hot weather marathons from hyponatremia than from heat stroke.

The issue is consuming a lot of water AND not replacing electrolytes. You basically sweat off all the sodium in your system. Because it is hot you don't feel so good, so you drink more water, thinking that will make you feel better. That causes you to sweat off even more electolytes, so you feel worse, so you drink more water .... repeat until you go into seizures. People do die from it. One of the issues is that early symptoms can look a lot like heat exhaustion, and late symptoms can look like heat stroke. However, just giving more water makes the problem worse.

Through the magic of Google I found a back issue of Boatman's Quaterly with a good discussion of Exertional Hyponatremia.

As with most things, the best treatment is prevention. When you are hot and sweating a lot, drink lots of water, but also eat salty snacks to maintain your electrolyte level!

Wow!

All those salt tablets we were fed actually had a rational purpose!

Hmm! Live and learn. I always thought potassium was the biggie in terms of becoming incapacitated via electrolyte depletion. Based on that, I assumed that the "salt pills" routine from ~50 years ago was a roundabout (archaic) way of getting trace amounts of potassium that are in most sodium salts.

Dealing with hyponatremia can be a very fluid situation, but any first aider worth their salt should be able to handle it.

Interesting. I'm surprised that in a situation where you're packing your own water, someone could drink enough plain water to induce hyponatremia.

It's a combo of drinking free water and losing salty water. Relatively easy to fix, a real PITA to diagnose, since it looks pretty close to heat exhaustion. In fact, a lot of times with patients I'll just recommend gatorade alternating with water for active folks.

Early on in our hiking adventures, a friend became very nauseous toward the end of a big hike on a hot humid day. That's when we became aware of hyponatremia.

On the hottest (90s), muggiest days hiking in Shenandoah National Park (Virginia), we've each packed a gallon of water/gatorade for a 9-10 miler with 2000-2500 foot elevation gain. We learned the hard way to go 50-50 with Gatorade/water.

On those hikes I've consumed 96 oz of water (3 Nalgenes) and sweated it all out.

I mean all of it -- no need to empty my bladder.



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For the sake of clarity, respiration uses a lot of water too. So you panted a bit out too.

Electrolyte packets ( gatorade powder) and bananas.

Apparently powdered Gatorade has been discontinued, at least here in SoCal. I have not seen it in stores for the last several months, ever since they commenced marketing the "new" formulations of Gatorade. Especially when exercising hard, I always liked Gatorade diluted 50/50 with water.

Were you looking for the individual packs? They might have just discontinued them but not the large cans.

What has disappeared is the "18.4 oz" orange plastic containers - far more economical than the individual packets. I also recycle/adapt the empty containers. They are useful for all kinds of things.

Surprising. You would have thought that just the local K-12 schools would keep them making it.

Still available on Amazon -- 18.4 ounce Powdered Orange Gatorade

The individual packs were not discontinued, I e-mailed them a while back when they were hard to find locally and they said they were going through a packaging change.
I found an online show store at the time who had a bunch in stock and ordered them.
Now I'm finding them in stores again but the packets are for 32oz bottles rather than 16oz so I have to close up and carry a 1/2 empty packet when I use one.
The G2 I still find in the packets for 16oz bottles but even though they say there is no sugar substitute in them I still get the funny after taste afterward. At least I don't get the headache like from a diet drink.

Very interesting thread. Thanks for the info.

A good, timely thread.

Hyponatremia is no joke guys. Years ago I was on a rim-to-rim hike in the Grand Canyon and unfortunately I witnessed a person almost die from hyponatremia. They drank a ton of plain water during the day while eating almost nothing. Late in the day they began to stumble, then couldn't stand, then slowly their mental status declined.

We managed to get them to an aid station where a doctor started an IV and we began to dribble sodium back into them. Their altered mental status precluded oral delivery of salt, usually done with saltine crackers and Gatorade. Beware, one of the symptoms of hyponatremia is extreme nausea at the thought of eating/drinking anything so the condition itself can put you in a hole that is very hard to dig out from.

They were helicoptered out, received 7 liters of slowly administered saline at the Grand Canyon clinic, and made a full recovery. The extreme degree of electrolyte loss affected this person's cardiac performance for about 6 months. The docs at the clinic see a lot of hyponatremia and have heard all the stories. Based on this person's history, the clinic estimated the person was only hours away from going into seizures, coma, and death before we got the initial saline on board.

A key to differentiating hyponatremia from heat exhaustion/stroke (without bloodwork) is history, history, history. The patient usually has ingested lots of plain water and has eaten little or nothing (at least not enough in proportion to the water).

A big piece of info for the history is urination frequency and volume. If a person is exerting themselves to the extreme they are losing lots of electrolytes and drinking plain water replaces the water but not the salts. So this person could have hyponatremia without a history of heavy urination.

But it is possible for a person to be drinking too much for the conditions, not exerting to the extreme, and this person is slowly diluting the bloodstream due to also not eating (enough). This person often has a history of unusually frequent, clear urination during the leadup to symptoms. This is what happened in the above case.

So it is critical when suspecting hyponatremia to get a good history, either from the patient if they can provide it or one of their companions. In the above case, the patient drank almost 2 gallons of water in not-so-extreme conditions, ate almost nothing, and was peeing a ton. The group's leader did a poor job of monitoring the food/water intake of his group and this bit them hard.

IMO the advice to drink until your pee is clear is overdoing it, much like "bring water to a boil then keep boiling for 5-7 minutes". In the field if my pee is light yellow that's good. Clear pee means I'm drinking too much and wasting resources.

I want to emphasize: hyponatremia is something you must work to avoid because once you're in it, you are in deep kimchee. The condition will make it hard for you to ingest what you need, and in bad cases makes it impossible for you to stand, let alone walk out. If you are solo you are hosed. If you're in a group, you will be an immobile casualty.

Very informative, thank you. I'm learning a lot from this thread.

Remember that the word "clear" is describing the clarity of the urine, different from the color of the urine which would be colorless, pale, light yellow, etc.

ASKAR - thanks ... needed that dude. HAHAHA!!!

I really didn't realize this condition was "real" - I've never seen anybody do this before. Wow - there must be a few people drinking tons of water out there. Just give them some powdered Gatorade.

Pete2

Glock - One question for you -- if a person is consuming that much clear water and not taking in enough electrolytes, wouldn't they notice that they were cramping up in their muscles before they get into a hyponatremia condition?

I'm one of those people who has issues with muscle cramping on a continuous basis and so I take additional calcium, magnesium and potassium to ward this off and to a lesser extent sodium. It would be impossible for a person like myself to NOT notice the severe cramps and hence realize the requirement for more salt and electrolytes right away. Other people's physiology will vary, but I just find it difficult to believe one could it sweat out and replace with only clear water and not be aware of any warning signs.

The signs and symptoms are pretty generalized and might not obviously be connected to salt deficiency. I went on a fairly long and strenuous hike amny years ago, ending up with a mild, but growing headache, and feeling slightly nauseous. We got home and reached for refreshments. I bit into a nice salty corn chip and it was delicious - I quickly had a handful more, slaking my thirst with the most delicious beer I have ever quaffed. More chips and another brew later, I felt fine and dandy. I got to thinking and reviewing my recent diet, finding that just by chance it had been remarkably electrolyte free. Again, by chance, I had carried no salty foods on the excursion. I had done plenty of hot weather hiking at the time, having lived in southern Arizona for about a decade, and the normal foods I consumed were adequate for electrolyte replacement, this trip being a startling exception.

If you would have uttered the work "hyponatremia" in my presence, I would have guessed that it was the name of a new rock band from England.

shot a 3 gun match Sunday, and the heat and humidity was brutal...I've been doing some internet research on DIY electrolyte and electrolyte/glucose replacement formulas...most of the time I drink 500ml bottled water, so reduced the formulas.. and am planning on making up some sachets of the mix... to mix as necessary

We saw er patients occasionally with hyponatremia secondary to water intoxication, stemming from a psychiatric diagnosis of one sort or another. They would present in apparent good health, no muscle cramping, perhaps some anxiety, but with serum sodium levels approaching the 120 meq/l level that may result in seizures. See reference here. . These were cases of chronic excessive ingestion of tapwater, so the picture might be a different in acute hyponatremia due to exercise.

I think it's a personal physiology issue. In the case I described above the person never complained of cramping before, during, or after the event.

Here is a good writeup on hyponatremia that is a nice balance between the medical-nerd physiology and the practical wilderness context.

Hyponatremia used to be a problem when Ebeneezer Goode was popular back in the early 1990s along with Chemical light sticks.

http://www.youtube.com/watch?v=4zlvvUYgR28

And BTW, this condition is not limited to outdoor or hot weather exercise.

There have been cases in the UK of people in nightclubs taking illegal drugs that tend to cause dehydration which is of course dangerous.
Advice was therefore given that users of such drugs should "drink plenty of water" some users took this to extremes and drank so much water that water intoxication resulted.

The symptoms could somewhat resemble those of drunkeness or recreational drug use, and might therefore delay proper treatment.