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Dehydration: When Should I Really Worry?

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Dehydration: When Should I Really Worry?

Aug 11, 2015
You’ve probably heard that once you feel thirsty, you’re already dehydrated. Dr. Scott Youngquist spills on daily water intake and dehydration: who’s most likely to need more water, how much you really need per day and how that can affect your day-to-day health. He talks about how dehydration can affect you in ways you may not realize and gives some tips to help you drink more water.

Episode Transcript

Interviewer: Dehydration. When should you really worry? We'll talk about that next with Dr. Scott Youngquist on The Scope.

Announcer: Medical news and research from University Utah physicians and specialists you can use for a happier and healthier life. You're listening to The Scope.

Interviewer: In the summer months you hear a lot about dehydration, and I've actually even heard that when you're thirsty it's too late. You're already dehydrated. So we're going to talk about that and other things about dehydration with Dr. Scott Youngquist. He's an emergency room physician at University of Utah Health Care. First of all, is there any truth to that, "When you're thirsty it's too late?" I'm already dehydrated?

Dr. Youngquist: There's some truth to that. That's not way too late, but it's a sign that you are dehydrated. That cotton-mouth, thirsty feeling is your body telling you it's time to get some more water.

Interviewer: I remember when I was younger nobody carried water bottles anywhere. You'd go out on hikes. My dad was a rancher. He'd go out and work all day and never take any water with him. Nowadays, you can't go anywhere without somebody having water. Is that silly or is that actually good?

Dr. Youngquist: That's a good question. One recent study suggested that children, at least, get not enough water during the day. So they're not drinking enough water for their regular needs and probably are going around in a state of constant dehydration.

Interviewer: I think I saw that study. They get a lot of juices and stuff like that but not actual water. Like a lot of kids don't ever drink pure water.

Dr. Youngquist: Yeah, absolutely. And some of those juices that are high in sugar actually cause you to be more dehydrated. So they will cause what's called a diuresis or cause you to urinate more fluids than you actually took in. So they can actually be a negative in terms of overall hydration status. And I think that some of the mild symptoms in kids, that are probably true for adults as well, are feeling tired, lethargic, not able to concentrate. Those may be signs that you are dehydrated.

And most adults like to start their day with a drink of coffee or several coffees during the course of the morning, which is also diuretic. Caffeine is something that causes you to urinate and it's also sort of a negative fluid. In other words, you'll pee out more than you took in with coffee alone.

Interviewer: So on a day-to-day basis, if I'm not necessarily super active or out in the sun working, am I probably not getting enough fluid and dehydrated? And is that a problem?

Dr. Youngquist: Yeah. It's only a problem if it causes impaired function for your day. So if you're feeling, like I said, excessively tired, trouble concentrating, and things like that, you may try drinking water.

Interviewer: So that's interesting. That seems like something I would never consider. I think, "Well, maybe I had too big of a lunch, or I didn't get enough sleep." But it could actually be water.

Dr. Youngquist: Yeah. Water could be a part of it. And a lot of people will get into a cycle of treating that with additional doses of coffee or Diet Coke or something like that. They're actually making their hydration status worse rather than better. So consider taking more water as one possible solution to that feeling you get in the afternoon.

Interviewer: All right, let's go outside for a second. On a 90 degree day, for example, I like to cycle or hike or do something like that. When should I start worrying if I don't have water? Like if I'm doing a ten-mile bike ride and I don't take water with me, is that a problem?

Dr. Youngquist: That's going to vary depending on how much water you had beforehand. So when you start out in the morning, actually, you haven't had anything to drink all night long. If you think about it, even fasted. You haven't had anything to drink. And most of your hydration status is actually come from mobilizing that's in your soft tissues. It's kind of accumulated in your feet and legs during the day through gravity. And that gets reabsorbed back into the vascular space while you're sleeping. But you can quickly become dehydrated in the morning without having enough hydration because of that, and you're actually have just urinated, not taken in any fluids at all.

Interviewer: So on a hike, say a couple miles, if for the most part I'm drinking water and I don't take water on that hike, and it's a hot day and I'm out in the sun for a couple hours, I'm probably going to be fine. It's just getting back to everybody's got water with them at all times.

Dr. Youngquist: Yeah absolutely. So it's going to depend on the duration of exercise, the amount of heat that you're exposed to, and your pre-exercise hydration status.

Interviewer: At what point should I start being concerned as a general rule, if I'm relatively well-hydrated most of the time?

Dr. Youngquist: Well, I'll give you just a general rule of thumb. I would say anything more than a couple of miles, you should probably bring some water.

Interviewer: Okay. And how much water should I be drinking every day? It tends to vary a lot. Like I've heard ten cups. I've heard as much as a gallon. Is there a general rule on that?

Dr. Youngquist: Yeah there is, and I don't know off the top of my head unfortunately, but there is.

Interviewer: Maybe ten cups is a gallon.

Dr. Youngquist: There is a calculation you could do, and you could look this up online, but there are various numbers given for the amount of appropriate fluids. We tend to calculate people's fluids on a maintenance basis when they come into the hospital and have to go without food or water because they're preparing for surgery or something like that. And for an adult we tend to go around 125 to 200 milliliters per hour as a maintenance fluid.

Interviewer: So what does that translate into in ounces then?

Dr. Youngquist: That's somewhere between four to eight ounces. So one half to a whole cup of water per hour is about what your maintenance requirement is.

Interviewer: While I'm awake?

Dr. Youngquist: Yes.

Interviewer: Wow, really? And how much should that increase when I'm exercising?

Dr. Youngquist: So you could probably at least double that when you're exercising. People tend to, instead of maintaining that fluid status, tend to get behind and catch up with a lot of water, and then get behind and catch up. So we don't consume that evenly throughout the course of the day, and it's probably impossible to do so. But that's why we have kidneys. Kidneys are good about conserving water when we need it and getting rid of it when we've got excess.

Interviewer: Can you drink too much?

Dr. Youngquist: You can, certainly. Yeah there's a phenomenon known as "water intoxication." You can get very sick from it. In fact, there have been some high-profile deaths from water consumption contests. There was a famous one, I think in California, where a radio station sponsored a water consumption contest, and I believe it was a female participant died shortly thereafter from water intoxication. So yes, you can drink too much.

Interviewer: But beyond that, I've heard that you could wash out all the good vitamins and minerals if you're drinking too much water. You could flush too much of the good stuff out of your body. Is there any validity to that?

Dr. Youngquist: I don't know about vitamins. It depends on if they're water soluble or not, but yes most of the time if you take supplemental vitamins most of it ends up in your urine anyway, regardless of how much water you take. And that's why you take some B12 vitamins and you'll notice that your urine becomes distinctly kind of dark yellow-orange in color, and it's not because you're suddenly dehydrated. It's because of the concentration of those vitamins.

Interviewer: So as long as you're doing about four to eight ounces, you're good.

Dr. Youngquist: Yeah. On average per hour.

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