A calm discussion of Hyponatremia

[David Thomas]

The Rim-to-Rim-to-Rim trip thread was getting contenous regarding possible mechanisms of developing hyponatremia which is low sodium levels in one’s blood serum.

I posed some questions about hyponatremia to a double-board-certified, American College of Physicans member, hospitalist/internist M.D. (who I met on a backpacking trip in 1993 and married in 1997).

Summary of our discussion:

How could an extreme hiker/runner get hyponatremia?

Short Answer: By drinking far too much water.

But the kidneys are very good at maintaining sodium levels in a tight range with greatly varying hydration levels. Yes, you can drink so much water that in absence of any salt intake, you could flush your kidneys of sodium which would in turn deplete your blood serum of sodium.

She then went on to list numerous medical conditions that could also lead to hyponatremia which shouldn’t apply to anyone thinking of a long hike much less a R2R2R.

Could a person develop hyponatremia from excessive use of electrolyte/runners drinks?

No. They could get volume-overloaded (especially with various (mostly serious) medical conditions) and that could create other issues, but since that water went in with sodium, it wouldn’t deplete sodium.

Extra credit question from the chemical engineer in the room: If you took potassium salts to excess in the absence of sodium, could you develop hyponatremia?

Extra Credit Answer: Potentially if you were giving only potassium salts but all runners drinks and supplements that have potassium have a balanced amount of sodium. She wasn’t sure, but suspected that serious, even fatal results (potassitum chloride is used in pet euthanasia) of high potassium would result before low sodium became an issue. i.e. you’d be dead of a potassium overdose before you developed hypothermia, but that was her guess – not a situation she’s managed or could imagine developing unintentionally.

She then discussed how they put a bit of salt and a bit of baking soda in water when they do oral rehydration therapy because the water is absorbed more quickly that way. Sugars also help the water be absorbed more quickly. So I suppose if you WANT to induce hyponatremia, huge volumes of salt-free, sugar-sweetened water without any salt in your solid foods would be most effective. So don’t do that.

I’m not doing 30-40 miles on free-range, low-sodium, steamed veggies and a few gallons an hour of pure water. I’ll be eating a lot of solid food – a fair bit of it prepared/processed with salt, maybe a bit of gel, some runner’s drink mix and lots of pure water to the point of peeing regularly. But HYOH, DYOD, EYOL.

-David

(hike your own hike, drink your own drink, eat your own lunch)
But, as I’ve posted under the trip thread, I will be bringing micro-brews to share, so you don’t have to BYOB. Nor fish – I’ll bring the smoked salmon.

[Art …]

David
thanks for your input, it seems to partially disagree with my understanding yet not totally disagree, as water is the culprit. need to digest it a bit.

water retention is a common issue and concern in ultras and seems to be associated with excess salt intake. A common understanding is that this is a forewarning of a hyponatremia issue. Perhaps this is not really the case.

[Jake D]

Thanks David, that is some great info. Best i could do was ask my friend who is a nurse who agrees with what they said. I could have asked my college adviser (who has a phD in athlete's nutrition) if i had a dog in the fight but i'm not going to call her over an internet debate.

I did not mean to have that get Chaffy but when someone calls ME out questioning my medical credentials (which i have) when that person does not I don't take it very well :)

seriously, have a kick@ss run/hike

[David Thomas]

Art: Thanks for your civility and grace.

You're right that too much salt can lead to too much water in the body. And that too much water can lead to hyponatermia.

But those aren't sequential – the first is under conditions of excess salt/water and the second is in cases of excess water/salt.

Maybe the bigger message for anyone who could seriously consider a R2R2R (i.e. decently healthy) is that quite large ranges of salt to water are tolerated just fine. Almost all of us get an excess of salt everyday but handle it fine. Most of us underhydrate around town and really need to hydrate better while on the trail. And my sense of the participants is that we've all got the miles under our belt to be reasonably safe.

I really liked Torrey's post about not skimping on water or food to save weight. You can finish a BPing trip without eating on the last day. You can't push yourself on a R2R2R if you short yourself in any way. The exertion, elevation, dryness, sun, and heat are all stressors that add up.

[Bob Gross]

If you want to look this up, you will find it easier as "hyponatremia."

–B.G.–

[Colin Krusor]

On longer hikes (longer than ten days), I carry a small whirl-pak of oral rehydration salts (ORS), which I made using a modified version of the WHO low-osmolarity oral rehydration salts recipe (I replaced the glucose with a mix of carbs). If you want to buy commercial ORS (ie, Ceralyte), it will cost you a fortune, but you can make several pounds of it yourself for a couple of dollars. I keep it in my first aid kit to prevent salt imbalance in case I get giardia/crypto on the trail.

[Ben F]

Colin, would you mind posting your recipe?

[Dave G]

An excerpt from a Runner's World interview with Tim Noakes MD, author of "The Lore of Running"
RWD: How and why do distance runners get hyponatremia?

TN: By drinking too much fluid during very prolonged exercise. We usually find that athletes who develop the condition drink between 1,000 and 1,500 ml per hour [between one and one and a half quarts] during exercise but sweat at much lower rates, perhaps 700-1,000ml per hour. As a result they develop a progressive fluid overload.

RWD: Who gets it most commonly and in what kinds of events?

TN: Women are at much greater risk than men for reasons that we don't yet understand. I think it is purely a size effect; women are smaller and more likely to develop a fluid overload simply because it takes less fluid for small people to become overloaded. Alternatively, it is clear that a big part of the problem is the inability of the athlete to excrete the excess fluid perhaps because of high levels of fluid-retaining hormones. It may be that woman have larger amounts of these hormones, the nature of which remain uncertain.

RWD: How can marathoners make sure they are getting enough fluids but not so much as to be at risk for hyponatremia?

TN: You have to drink a lot for a long time to develop a fluid overload. If runners are drinking less than 1 liter per hour, they are unlikely to develop the condition. Since you need to keep drinking for 5 to 6 hours or more, only very slow marathon runners and ultradistance endurance athletes are at risk.

The best thing for athletes to do is to weigh themselves before and after a hard training workout to determine their usual sweat rate. Then they can plan their fluid intake during a race accordingly.

RWD: How can runners or medical personnel spot hyponatremia in another athlete?

TN: Aside from some medical conditions that are usually well recognized, there are really only two conditions specific to sport that cause an altered level of consciousness during prolonged exercise: heat stroke and hyponatremia. Measuring body temperature is the first step in the differential diagnosis. If the body temperature is above 42 degrees Centigrade, the diagnosis is heatstroke, and the athlete must be placed in an ice-water bath for 5-10 minutes to lower his or her body temperature. If the temperature is normal [i.e., 38-40 degrees Centigrade], then the most likely diagnosis is hyponatremia. The diagnosis can be confirmed by measuring the blood sodium content, and obtaining a result below 129 mmol per liter.

End excerpt.

Dave

[Steven Scates MD]

Hi All,

There is one other thing to think of that I have come across not mentioned above. Athletes don't always admit it, but some have hypertension and are taking diuretics. These drugs frequently cause hyponatremia, as the patient will be urinating salt water at about 60 mEq/L under the influence of the drug, then they get dry and thirsty. They replace the deficit with water, thus diluting the serum sodium. I have seen the sodium less than 120 mEq/L rarely from this alone.

It is true you can just drink too much water. I saw a man when I was still in medical school who drank 13 liters of water daily. He managed to wash out his kidneys quite nicely and his sodium was very low. Obviously, he worked at it, but even lesser amounts of overindulgences can drop the levels down.

Not everyone is up front about their medications. Overall, diuretic use is close to number one on the causes of hyponatremia list and we see it all the time.

If someone has mental status changes from hyponatremia, I put them in the hospital quickly.

Thanks, steve

[DriCamp]

Thanks to Dave and other thread contributors for the insightful research and report; better info than I was able to find elsewhere!

Being new to BPL, I don’t have a sense of whether it’s acceptable to revive a decade old thread. (On some forums, people just freak toxic green if a “vintage” thread is revived; others are cool with it, realizing that (1) the information hasn’t expired and (2) the poster has responsibly used the search function. Apologies if this is the former type of forum.)

I’ve been trying to research hyponatremia to see if my beginning-of-hike routine is dangerous. In the hour leading up to a hike, I’ll drink around 1.5L of water, sometimes closer to 2L, which can mean the first 2 or 3 hours of trail time require no additional drinking. I’m curious if I’ve been flirting with hyponatremia, and after reading this thread, I’m thinking, no. No diuretic use, no symptoms other than having to water the plants periodically.

But I have been wondering if that second liter should be Gatorade or my home-brew pink-salt-&-sugar mix. What do you think? Is tanking up on 2L of water before a hike, asking for trouble?

(The mix, if interested: 2T sugar, 1/8t pink salt, 4 oz of any kind of juice, fill to the top of an empty 20 oz Gatorade bottle).

[Matthew / BPL]

My perception is that BPL does not freak out about bumping old threads. This is an interesting thread that I hadn’t read before. I’m glad you bumped it.

I don’t have much to add to the discussion other than a hunch you are not risking hyponatremia by drinking 2L of water and then not drinking for a couple hours of hiking. If hyponatremia was that risky for hikers who are not on meds I think we’d be reading about it constantly.

[Axel J]

My mantra has always been  drink only when I’m thirsty and be on the lookout to avoid sodium packed meals but I was made aware of this condition when a dear friend called 911 and was taken to the hospital earlier this year. The diagnosis, hyponatermia and pneumonia. He is an older active gentleman with no history of forcing fluids. After a week in the hospital, he was discharged with a strict regimen of restricting fluids but no clear  etiology of the sodium imbalance. Maybe the pneumonia had something to do with it? The impression I got after witnessing my friend suffer the affects is it’s a complicated medical condition where the body for some reason is unable to normally process sodium, so I’m not sure how easy it would be for a healthy person to induce the condition by just forcing fluids.

One of my loves for backpacking is to quench a well earned thirst with some cool mountain spring water. A true natural high that never gets old.

[jscott]

My strong impression is that folks who freak out about the (highly, highly unlikely) onset of hyponatremia are most likely to suffer from dehydration. We all should read the recent account of a couple, their baby and a dog who died from dehydration while hiking up from the merced river near Mariposa.

How many of us have ever drunk a liter of water every hour for 6 or 8 hours?

[Rex Sanders]

… risking hyponatremia by drinking 2L of water and then not drinking for a couple hours of hiking.

If that were true, I’d have died many times by now :-)

— Rex, ex-desert-rat-who-learned-to-drink-less-elsewhere

[Todd T]

Tanking up before a hike is hardly uncommon.  Just eat salty snacks now and then and drink all the water you want, probably more.

[Steve S]

Situational hydration can be somewhat more nuanced. Another wrinkle is habituation to high temperature exercising. IIRC, research into heat adaptation has shown the body conserves sodium but not potassium in sweat after adaptation.

One first hot day of the year ski-backpacking trip, while carrying skis along an approach trail, I and a companion ran into steep snow. I kicked big steps into the slope to ease things for my companion so we could access a flatter area above where we could begin to ski. Kicking steps in hard corn snow for 100-200 foot of elevation gain in the sun with a pack led to much sweating. Thirsty, I drank. I had a headache for the rest of the trip. My companion failed to inform me that I had lines of white crusts of salt visible around my face — he, utilizing the steps, did not show loss of salt.

[Adam Kilpatrick]

Hi Dricamp. I’d be suprised, being otherwise healthy, if you caused a noticeable hyponatremia from drinking 1.5-2L in one go, unless you keep sustaining that rate through the rest of the day.

We regularly bolus patients with decent amounts of fluids in ICU if we think they are hypovolemic (low blood volume) and think it will get their blood pressures up. We monitor their bloods closely (eg we can do near instant arterial blood gases…). The changes are relatively slow. And when I mean bolus, this fluid is going direct into the blood stream. Your’s is going via your gastric system, etc, first.

The main issue will be that unless you are greatly dehydrated already before you do it, you’ll probably mostly pee it out fairly quickly and not get a huge amount of benefit from it, past a few hundred ml or so. Hard to say exactly, depends on a ton of factors. 2L is probably a bit extreme and pointless unless you feel really thirsty and know you haven’t drunk anything for a long while (eg a couple of hours before bed, then slept ten hours, and its been a warm night…).

Generally for most people, your nephrons know what to do; drink to thirst.

Oh, another thing that popped into my head reading this thread for people thinking of playing with adding salts; don’t go too fast! If you are hyponatremic, we don’t raise Na levels too fast… don’t go and eat a whole bag of salt. How fast and how much to take? Well that’s kind of tough. We start with something (eg we might start a bag of 3% NaCl… “normal saline” (same as your blood when its normal) is 0.9% running at maybe 100ml/hr, but we’ll adjust by doing regular blood gases, at least every 4hours. Titrate to effect.

Like the MD said above… if you are symptomatic of hyponatremia (been sweating a lot in a tough marthon esque endurance effort, and, you have reduced consciousness) your best bet is to get to hospital. If your GCS (Glasgow Coma Scale) is low, you really need to be in an ICU bed. Priority should be contacted emergency services for advice and evac.

[Jerry Adams]

what David Gray said in 2012 seems reasonable, to get hyponatermia you should drink 1 to 1.5 liters of water for 5 to 6 hours

that seems like more of a problem for marathoners than backpackers

but, I don’t see the need to have a several liter hydration bladder and sip water constantly like some backpackers I have seen.  Little risk of hyponatermia though – you’d have to carry at least 5 liters of water

[David Thomas]

10 years later, I’m still on BPL, and I’m planning another GCNP trip.

DriCamper: I’m a gulper not a sipper and will “camel up” with a liter of water at the trailhead, sometimes having drank another liter earlier on the drive to the trailhead.  Then, I’m good for several hours without carrying water or stopping to treat some.

The fatality that comes to mind was a 2007 Sacramento radio show contest, “Hold your Wee for a Wii” in which contestants sat at a table drinking gallons of water and nothing else, the last one to pee won a game console.  A 28-year-old woman called in to work to say she was in terrible pain; her mother found her dead.  Woman are at more risk of hyponatremia that men, for poorly understood reasons.

[DriCamp]

David Thomas! Thanks for posting. You don’t know this, but I’ve been a “student” of yours for at least a decade, studying your posts, and learning from your experiences. I’ve quoted you as an authoritative source to friends on many occasions – this, despite the fact we live in nearly opposite environments, temperature-wise! Thanks again for starting this thread.

[jscott]

I sometimes suffer from Hippiecalifornia.

[DriCamp]

Interesting: Page 173 of Skurka’s 2nd Edition of UHG: “In an effort to prevent dehydration, I have also consumed too much water and become hyponatremic, whereby the concentration of sodium in my bloodstream was too low to absorb the water I’d ingested. On my first real desert trip, I recall feeling tipsy while leaving several water sources, where I’d knocked back several quarts in half an hour.”

The implication being that possibly 2L (“several”?) of water drunk in 1/2 hour might start HN.

Next page he writes: “I’ll consume one to two quarts of water within the first hour of the day; I’ll drink heartily at a water source (“cameling”) before a long dry stretch…”

The implication here being that 2L drunk within an hour is appropriate.

I realize that there are other variables, and that I’m being literal with my interpretation of ‘several,’; it’s just noteworthy when a renowned expert indicates that 2L in a half hour is too much, but 2L in an hour works fine (for him).

And finally, this, just because it’s interesting: “Kidneys can process only about one quart of water per hour.”

[AK Granola]

I know nothing about hyponatremia, but I always start every long hike or marathon with downing a liter or so of water before I leave and have a 16 ounce Gatorade bottle with electrolyte solution (not usually Gatorade) to sip on as I walk. I never believed much in electrolytes but recently they seem to make a big difference in preventing overall fatigue earlier in the hike. Fewer cramps too. Maybe that’s all mental, I have no idea and don’t care, because it works either way. I also have boosted saltier foods since doing longer trails. I have a wicked sweet tooth, but could not eat a single dessert on my recent Tahoe Rim Trail hike. I ended up pitching all the dessert things into the trash at my resupply, and added Fritos, pretzels, and more salted mixed nuts. Now back at home on the couch with winter setting in, big cinnamon rolls are like crack, my Kryptonite.

Anyway, I can’t imagine getting any medical condition from drinking a liter to a liter and a half of water before starting out on some vigorous activity. I wouldn’t worry about it for myself.

[Author]

Posts