Hematocrit & Hemoglobin differences in dehydration vs blood loss - page 2

by mreicher

36,912 Views | 14 Comments

I'm wondering what the difference would be on the CBC for hemoglobin & hematocrit for someone with a fluid volume deficit depending on whether they were dehydrated or had blood loss.... Read More


  1. 6
    Quote from mreicher
    But if you're losing blood, the percentage of H & H in the remaining blood is the same, no? Let's say you have a liter of blood(making up easy numbers), 20% of which makes up your H&H. You lose 1/4 of that blood. The remaining 3/4 of the blood is still comprised of 20% H&H, no?
    I get the dehydration example, but our texts lists dehydration & blood loss under fluid volume deficit & indicates that in both instances the H&H would be increased......
    This is why NANDA needs to go (actually one of many reasons). Fluid volume deficit is a NANDA nursing diagnosis, which usually does more harm than good by lumping different medical conditions that have very different medical and nursing assessments and interventions into the same vague category.

    In both blood loss and dehydration you will have an overall lower fluid volume, but what makes up the remaining fluid can vary. With dehydration, you are lacking in the fluid component of blood, which causes hemoconcentration and will cause the H&H to be skewed higher. Blood loss will cause a loss of whole blood, your body will then try and compensate of the loss of total volume by shifting fluid into the circulatory space which then causes hemodilution, or a relative drop in H&H.

    Avoid NANDA, or at least store all NANDA related info in a part of your brain where it can't interact with information that is actually correct. Rather than fluid volume deficit, think of these two very different problems as what they are: dehydration and anemia.
  2. 3
    Okay, not trying to do the homework, but I think the OP (original poster) is confused and is really not getting it.

    Think of it like this. You dissolve 1/4 cup of salt in 1 cup of water. The salt represents the hemoglobin/hematocrit. Now boil that water, the salt content increases as the water evaporates. Same as dehydration, as plasma/fluids decrease the concentration of red blood cells/hgb increases.

    So take that same cup of water with the 1/4 cup of salt and pour half of it out. You no longer have the same amount of salt or water. You have less of both. Same as with blood loss you end up with fewer red blood cells and less plasma. Sure, it might be in a similar solution, but less of both.

    Now, if you check a H&H on a patient with new bleeding, you won't see much change in the H&H at first because, as you pointed out, the concentration of the solution is similar as it was before the bleed. BUT since there isn't enough fluid, the body starts to compensate by drawing fluid into the vessels to increase plasma. Once that happens you see the H&H drop.
    RNam, resumecpr, and TNgirl2010 like this.
  3. 0
    Quote from mreicher
    But if you're losing blood, the percentage of H & H in the remaining blood is the same, no? Let's say you have a liter of blood(making up easy numbers), 20% of which makes up your H&H. You lose 1/4 of that blood. The remaining 3/4 of the blood is still comprised of 20% H&H, no?
    I get the dehydration example, but our texts lists dehydration & blood loss under fluid volume deficit & indicates that in both instances the H&H would be increased......
    Actually, it depends on whether or not the H&H will remain the same. It would remain the same if and only if the loss is an isotonic loss, RBCs, and serum components are lost in equal proportions. It is possible, and quite a risk factor for there to be alterations in H&H as I mentioned in my original answer. I verified this in Joyce Lefever Kee's "Laboratory and Diagnostic Tests". You raise a good point, though.
  4. 11
    Quote from CCL RN
    Here someone is trying to help the OP think a problem out and someone always comes along and just does the work for them. Always.

    Sigh...
    It's not a matter of doing the work for them. Most likely the individual had thought about it beforehand. Besides, why do we need to be so stingy with information? I am personally glad to help other people advance their knowledge base in any way we can. Think of when you were in nursing school. Sure you wouldn't want you professor to brush you off when you asked a question, even if the professor thought you hadn't thought it out that well.

    Let's just try to help each other here. It will help us provide better care by sharing knowledge.
    CamelliaJJ, RNam, sashamay, and 8 others like this.
  5. 0
    heaviest cells white=lighter plasma=even lighter
    [00000000000000000000000|0000|[color=sandybrown]0000000000000000]
    rbc wbc serum/plasma
    ok that's a tube of normal blood.hold i t down the red cells are at the bottom, the white cells are in the middle and the liquid part is at the top.

    in dehydration you lose fluid., you have the same amount of rbc as you weren't losing them or the white but the liquid part went to try to build up what dehydration cost.

    so in this tube let's say the normal rbc is 16 (hgb). the hct would run about 48.

    so the hct is normally near 3x the hgb.

    heaviest cells white=lighter plasma=even lighter
    [000000000000000000000000000[color=sandybrown]0000- [lost]
    [color=sandybrown]
    if you lost most of your liquid/plasma in dehydration the percentage of red cells in this tube would be higher and the hct would be higher. you replace body fluid, it gets transported in the blood, and the hgb goes back to normal.



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