Hematocrit & Hemoglobin differences in dehydration vs blood loss

Nurses General Nursing

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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.

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OK, now think of what you just wrote... take it apart, don't overthink it.

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I've been thinking about it.....can't come up with a difference, which is why I asked.

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Define Hematocrit

Define Hemoglobin

Define blood loss (hint: some blood is gone...)

Define dehydration (hint: blood is not leaving... but there is a change... )

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Specializes in Vascular Neurology and Neurocritical Care.

Hematocrit:

With blood loss, the hematocrit will be diminished due to blood loss which certain will include loss of RBCs (severity of decreased hematocrit dependent on severity of blood loss.

Dehydration is loss of body water but RBC concentration as is, so the hematocrit will be increased as compared to everything else.

So, in review, hematocrit increased w/ dehydration, decreased with blood loss.

Hemoglobin:

Decreased in blood loss due to RBC loss, which is where hemoglobin is bound.

It will be increased with dehydration because there is a loss of body water. Remember that since hemoglobin is bound to the RBCs, if the RBCs are increased, then so will the hemoglobin, and vice versa. Can't think of an exception, but someone will correct me if so.

Let me know if you have further questions.

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Hematocrit:

With blood loss, the hematocrit will be diminished due to blood loss which certain will include loss of RBCs (severity of decreased hematocrit dependent on severity of blood loss.

Dehydration is loss of body water but RBC concentration as is, so the hematocrit will be increased as compared to everything else.

So, in review, hematocrit increased w/ dehydration, decreased with blood loss.

Hemoglobin:

Decreased in blood loss due to RBC loss, which is where hemoglobin is bound.

It will be increased with dehydration because there is a loss of body water. Remember that since hemoglobin is bound to the RBCs, if the RBCs are increased, then so will the hemoglobin, and vice versa. Can't think of an exception, but someone will correct me if so.

Let me know if you have further questions.

Where where you when I needed someone to do *my* homework?

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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......

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Specializes in Cath Lab/ ICU.

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...

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@CCL RN-what's an OP? I don't mind the help Future NP BC was giving. I've been trying to work it out for hours, and the way onaclearday was trying to 'help me think it out' wasn't working at all. Either way, I'm still confused.

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Specializes in CRNA.
Hematocrit:

With blood loss, the hematocrit will be diminished due to blood loss which certain will include loss of RBCs (severity of decreased hematocrit dependent on severity of blood loss.

Dehydration is loss of body water but RBC concentration as is, so the hematocrit will be increased as compared to everything else.

So, in review, hematocrit increased w/ dehydration, decreased with blood loss.

Hemoglobin:

Decreased in blood loss due to RBC loss, which is where hemoglobin is bound.

It will be increased with dehydration because there is a loss of body water. Remember that since hemoglobin is bound to the RBCs, if the RBCs are increased, then so will the hemoglobin, and vice versa. Can't think of an exception, but someone will correct me if so.

Let me know if you have further questions.

That is not exactly the best way to answer that question. Mreicher pretty much was correct in regards to blood loss. Think of a bag of packed red cells. The hematocrit averages 70%. Pour out half of the blood and while the volume has decreased the remaining blood will still have a hematocrit of 70%.

In acute blood loss doing a CBC will not help. There would be no difference between hemoglobin and hematocrit from what it was before the bleeding occurred. After a few hours plasma volume will be replaced by fluid from the interstitial space and you will then see a decrease in H&H. Also, there are many other methods that aid in assessing blood loss and volume deficit. Lactic acid and base excess are a good place to start looking if you want to read into this topic further.

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Specializes in Critical Care.
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.

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Specializes in Family NP, OB Nursing.

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.

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