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How much can dehydration elevate hemoglobin/hematocrit blood test results?

post #1 of 14
Thread Starter 
Hi. I am just wondering if anyone know how much higher dehydration can make hemoglobin/hematocrit appear. I recently spent the day in the hospital due to dehydration resulting from hyperemesis. I had been worried that I was getting anemic because I had also been blacking out on a regular basis (several times a day). They took my blood and tested the hemoglobin/hematocrit, etc., but did so before I received the IV fluids. They later told me that ll my blood test results were normal, and that the hemoglobin/hematocrit are in the low-normal range (I don't remember the numbers now, but they were in the low part of the normal range). Since I have been rehydrated and taking meds to control the nausea and vomiting, I have still been experiencing the black outs. It happens less frequently, but I still wonder if I might be anemic since my hemoglobin/hematocrit levels could have been elevated by the dehydration when the blood was taken (they had to stick me 4 times before they could get a vein...). Should I ask for a retest? I am scared of hurting myself with all this blacking out. Yesterday, I shut my finger in our heavy front door because I started to black out as I was closing it. That one was no biggie, but I am afraid to fall down, etc.
post #2 of 14
I've never heard of this happening.

I wonder if your fatigue and light headedness has more to do with your severe hyperemesis. ?
post #3 of 14
Thread Starter 


It certainly could be.

At my first midwife appointment, the midwife told me that blacking out is normal in pregnancy (although it doesn't seem normal to me, lol), although if it happens frequently, it could indicate anemia. So that's where I'm getting this, but I don't know...
post #4 of 14
I had that trouble late in pregnancy with my first, and found that the more water I drank, the less dizzy I felt.
I have pretty low blood pressure, so I wonder if being better hydrated helped keep my volume up, and therefore my bp?

I know I feel weak and dizzy when I've been throwing up, and not eating well

But then, another blood test couldn't hurt, either, right?

Good luck. It is a scary thing.
post #5 of 14
ah, yeah, I see that being lightheaded and fatigued could be anemia, but if your iron levels are good, I wouldn't think that could be the case at all.

I would, however, look at some simple ways to get protein in you every few hours if it's possible. Hyperemesis sucks.
post #6 of 14
Thread Starter 
Yes, hyperemesis sucks.

I guess my point was that being dehydrated would/could make my hemoglobin/hematocrit appear normal when in fact it isn't. Does that make sense? Maybe I don't understand how these things work; I'm not a medical person. I read that one cause of elevated hemoglobin/hematocrit is dehydration (because the blood is more concentrated at that time). So I thought that if I was dehydrated that would tend to concentrate my blood so that the hemoglobin/hematocrit levels appear normal, although if I had been hydrated properly, my hemoglobin/hematocrit would have been at a low/anemic level (as my blood was thinned by my being hydrated, the same red blood cells, or whatever is being measured, I'm not sure would be less concentrated). Does this make sense? I don't know... Sorry.
post #7 of 14
Thread Starter 


Just wanted to say that probably pamamidwife got what I was trying to say, but had never heard of that happening. Sorry, communication problem is probably with me.

Off to try to get some protein in me.
post #8 of 14
Yes, dehydration can definately cause your hematocrit level to be elevated. I am an ICU nurse, just so you know where i am coming from, but yes to answer that question, yes. So sorry about the hyperemesis I hope you feel better soon.
post #9 of 14
Kimberly, so, it would affect the hct because of the low plasma/fluids, but it wouldn't affect the hgb, right?
post #10 of 14
Ooh good question. I have never seen a hematocrit and hemoglobin not maintain their usual ratio (hematocrit is about 3 times your hemoglobin level) nomatter what the patient's fluid status was. But I could be wrong. I did just make rounds around my unit and asked the doctors and other nurses who are on today ( I would feel stupid if I told you what I thought without getting some second opinions and I was wrong lol!), they seem to think they should both reflect the same dehydration status, I also asked my old respiratory department where we test hemoglobin and hematocrit with our blood gasses and they seem to think the same thing too. That isn't to say all of us are wrong and we just don't know it, YK? But everyone seems to think the hemoglobin would be elevated as well in the case of dehydration.
post #11 of 14
Actually, the hemoglobin is a measured protein level while the hematocrit is more of a concentration. The hemoglobin value will be the same, regardless of hydration status, while the hematocrit may be affected by moderate to severe dehydration. The truth is, they both may change a little, but usually not enough to be low/normal while dehydrated to low enough to result in black outs once rehydrated.

Hope you are feeling better soon!
post #12 of 14
So the hemoglobin will stay the same? Interesting. I have never seen the ratio change much at all, nothing remarkable. Ha ha! Now I get to go tell everyone here they were wrong. Some of the NP's were pretty adamant that they were right and thought I was dumb for even questioning they might not maintain the same ratio all the time LOL!

Re: how they are measured, yeah, they are definitely totally different (hemoglobin measuring a percent of the total volume and hemoglobin, like you said, measuring the protein.) but even when I ran the lab up there I was tought they correlated all teh time, though admittedly I don't recall discussing dehydration and if it changes that "normal" ratio. Hmmm, that is interesting though. I am nervous to talk to the ones who were SOOOO sure, tell them they are wrong too, but I want to (where is that little devil smiley).
post #13 of 14
Thread Starter 


Well, this has been an interesting discussion.

Both my numbers were in the normal range, so I guess that's not my issue. I have noticed the black outs get worse as I get more dehydrated, so it may be that alone.

I suppose I've gotten rather brainwashed into thinking I may be anemic. Every appointment I go to the health care professionals *love* to tell me I'm probably anemic, because I'm vegetarian. Also, my relatives like to claim that one, too: "You're so pale. You look anemic; maybe you should change your diet," etc. I have started to believe them, lol.
post #14 of 14


The flip side of the coin is that when you have been rehydrated in a hospital, your HCT may drop significantly as blood is diluted by IV fluids. Just thought that was interesting to add. No harm in a re-test, though. Glad you got some medical care. It seems that blacking out can be a bunch of things, but if you see some difference with keeping hydrated, that seems to be your best bet. Nausea can really do a number on you as well. I can get pretty darn dizzy while something is making my stomach turn.

Good luck--
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