Hematocrit (Hct) Lab Values

For this lesson we're going to talk about hematocrit.

Now before we get started the thing that you need to know about hematocrit is that it’s measured in percentages, which will get into in a minute. But for our male patients this is really going to be similar to the red blood cells and the hemoglobin in that the male percentages are going to be slightly higher than the female. So 41 to 50% is normal for a male patient and a female patient is normal hematocrit is going to be right between 36 to 44%.

Like I said the important thing to know about hematocrit is that it is measured in a percentage. And when I say percentage what I'm talking about is that it's a measuring the actual packed red blood cells compared to the total blood volume. So if you look at this tube we're looking at the percentage of the erythrocytes, are the red blood cells in relation to the whole volume of the blood. So in this tube, 45% of the volume is erythrocytes, and the other 55% is plasma and other types of cells in the blood. So this says that the hematocrit of this patient is 45%.

One of the benefits to hematocrit is it it helps to quickly indicate certain conditions like anemia, or other conditions where you have really high hematocrit levels. It gives a quick reference into what's going on with the patient in terms of their overall blood volume, and any other problems. It's often measured with hemoglobin, and you need to be mindful of what the red blood cell count is because all of these things typically Trend together.

I definitely recommend that you check out both the lessons on hemoglobin and red blood cells so that you can get a better understanding of how these three lab values all play together.

What do we need to be mindful of when we are submitting hematocrit levels to the lab?

So the first thing you're going to want to do is it's typically submitted in a lavender top tube, that has a EDTA in it. EDTA is going to keep the blood from clotting, and it also helps to get an accurate measurement of percentages.

Just like with hemoglobin and red blood cells, how you get the blood and how you put it into the tube is vitally important. What we don't want to do is cause hemolysis, or breakdown of those red blood cells, because we both forced those red blood cells through a tiny opening or with too much pressure and it breaks them down, and then you're not going to get accurate measurements. So make sure that you were introducing them slowly, pay attention to facility policy and terms of putting blood into blood tubing, and also consider the size of the gauge of the needle is that you’re drawing with. If you are drawing blood to a really small needle, or a small amount of tubing, or you're applying too much pressure, it could cause a breakdown in those red blood cells, and then the measurements are going to be off, not only in the hematocrit, but also theoretically in the red blood cells and the hemoglobin.

Now let's take a look at some abnormal lab values for hematocrit.

With increased hematocrit, just like with red blood cells, and hemoglobin, dehydration can cause a change in the percentage of the total blood volume, and that can actually increase the amount of red blood cells, and in theory the Hematocrit. Also think about respiratory disease. If you have a disease that is requiring an increase in oxygen, the body compensates by kicking out more red blood cells, and therefore will cause an increase in the hematocrit. These are diseases like pulmonary fibrosis and COPD. Because there is a higher need for oxygen, the body is going to respond by producing more red blood cells because it thinks that it can get more oxygen delivered to the tissues by that pathway.

Polycythemia vera is another one that you'll need to pay attention to when you see an increase hematocrit and it's probably going to be the one that's going to knock your socks off, because the hematocrit is usually extremely high. Polycythemia vera is an illness where you have a major overproduction of red blood cell counts, and it's going to cause the hematocrit to jump excessively high. The way the providers typically treat this is through bloodletting, so literally pulling off large quantities of blood, in order to decrease that hematocrit level, in Austin you can use to increase water intake and also by some medications.

What if the hematocrit is low? Decreased hematocrit levels are often caused by some sort of blood loss, whether this is through some sort of surgery, or trauma, or some other sort of hemorrhage. You're going to want to make sure that you stop deleting your patient and you may typically also do blood transfusions if they're at dangerous levels. Other reasons why you may see decreased hematocrit are through types of anemia, like sickle cell anemia or aplastic anemia. You also may see relative anemia that's associated with pregnancy because the increased total volume of plasma. Another time that you may see and anemia is from the decrease in the hormone erythropoietin, that's caused by kidney disease. The kidneys are where EPO is produced, so if they're damaged they're not going to produce it, and therefore you're going to have no stimulation from the kidneys to tell the bone marrow to secrete red blood cells.

You may also see decreased red blood cell production with diseases like leukemia, because the bone marrow production is so vastly affected by the cancer. You can either do chemotherapy, radiation, bone marrow transplants, or other methods of treating leukemia to help bring that hematocrit level back up.

For nursing concepts for this lesson, we really focused online values, and oxygenation, since hematocrit is in direct relation to the red blood cells would carry oxygen to all of our tissues.
So let's recap.

Hematocrit is a percentage, and it's related to the total volume of blood.

When you're looking at hematocrit, also consider your red blood cells or hemoglobin counts, because they're almost always tested together.

You always want to send hematocrit samples in the lavender top tube, and be careful not to cause hemolysis with technique.

When you have elevated hematocrit counts, it's because there's an increased need for oxygen and the body is responding by over producing it, or you actually have an overproduction of those red blood cells causing the hematocrit to be increased.

And finally when you have a decreased hematocrit, often look to blood loss or decrease red blood cell production as the call Britt.

That's our lesson on hematocrit. Make sure you check out all the resources attached to this lesson. Now, go out and be the best selves today. And, as always, happy nursing!!