Understanding Anemia Diagnostic Tests and Anemia Causes
Medical laboratory scientist. Dr. Kyle Riding discusses testing involved in determining anemia types versus some other blood disorders and how results are used to determine causes of anemia.
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In this program:
What tests are used to determine anemia diagnosis and causes? Medical laboratory scientist. Dr. Kyle Riding discusses testing involved in determining anemia types versus some other blood disorders and how results are used to determine causes of anemia.
Transcript
Deandre White:
So to shift into another chronic illness that is very, very common, anemia, what is the connection between iron and anemia? And if a patient has low iron, will this throw off the CBC reading?
Dr. Kyle Riding:
So iron deficiency is the most frequent cause of anemia. So to talk about anemia, we need to actually talk about our little red blood cells floating around in our blood. And so red blood cells are made in our bone marrow, and their job is to carry oxygen to our tissues and then bring carbon dioxide back to our lungs. So they're really important for gas movement in our blood. And to be able to carry oxygen, those red blood cells need a compound called hemoglobin inside of them, and that hemoglobin has an iron molecule in it that helps with the oxygen transport. So patients that have an iron deficiency, for whatever cause of the iron deficiency that may be there, okay? They can't make hemoglobin at a normal rate, which means they become anemic. They're just not able to carry oxygen appropriately.
So what will happen is a patient with iron deficiency will see a reduction in their hemoglobin and hematocrit values because the bone marrow just can't make the right amount of it. Additionally, one of the other telltale signs is a reduction in the size of the red blood cells. So the MCV, which stands for mean corpuscular volume, big fancy title for just a way of telling red cell size, will be reduced. Because the bone marrow in kind of a reactionary step, it's like, "Ah... " which means that it's going to make smaller ones.
So in terms of iron deficiency and the impact on your CBC or complete blood count, you're going to see a reduction in the hemoglobin, a reduction in the hematocrit, and a telltale sign that it could be iron deficiency anemia is a reduction in what's called the MCV, which stands for mean corpuscular volume, which is a really fancy way of saying how big each red cell is on average. Now, the reason we see the MCV go down in iron deficiency is because the bone marrow goes, "Ah! I'm not making enough hemoglobin." So its reaction is to make more red cells, but those red cells are made smaller. So that is why the MCV goes down. So in terms of what you'll typically see, the most telltale signs of an iron deficiency anemia, low hemoglobin, low hematocrit, low MCV, and that's what you should be looking for. But there's many other causes of anemia that really need to be examined if iron deficiency is not confirmed. So don't...it drives me nuts when the assumption, particularly in women of childbearing age, it's assumed that they're iron-deficient, because it's not always the case.
Deandre White:
You explained that perfectly, I just want to say hemoglobin is my favorite protein so this stuff is kind of exciting to me.
Dr. Kyle Riding:
It's a good protein.
Deandre White:
Yeah. But according to the American Society of Hematology, over 3 million Americans, including those young women have anemia. So can we just dive more into what anemia is and the most common cause if not iron deficiency?
Dr. Kyle Riding:
So anemia is basically, it is a reduction in the blood's ability to carry oxygen. That would be its technical definition. It’s more practical definition is a reduction in hemoglobin where you're not able to meet the oxygen-carrying demands in the body. Now, iron deficiency is the most common form of anemia, but there's some other very common forms of anemia out there. Other causes include vitamin B12 or folate deficiency. Those are dietary deficiencies that can lead to anemia. Those deficiencies can actually also be caused by in kind of older school but still used chemotherapies that are out there. Additionally, we have to remember, conditions like sickle cell disease is a form of anemia as well. And there's also another inherited disorder called thalassemia, which is when genetically you don't inherit the genes or you don't inherit some of the genes needed to produce normal hemoglobin. So your body doesn't have the cookbook or the instruction manual to make the hemoglobin.
And so when it comes to testing for anemia, I tend to break it down this way for a patient, easiest way, and it's still all not that easy at times. If you are anemic, so your hemoglobin is low, typically a low hemoglobin, you want to see something less than a 10 grams per deciliter hemoglobin because that is suggestive of a functional anemia. You could be slightly below the reference range but not be truly...anomaly, but you're not anemic. The next test to look at is the MCV. Okay? If the MCV is low, if it is low, you should work with your provider to have iron studies done. Things like a ferritin value should be determined.
Deandre White:
Okay.
Dr. Kyle Riding:
But that low MCV could mean it's iron deficiency. It could mean that you have chronic inflammation that is impacting your bone marrow's ability to produce healthy red blood cells. It could be thalassemia. It could be a host of other iron-related conditions. So a low MCV, start with the iron studies. If the iron studies don't tell you what's going on, then genetic testing for thalassemia may be required. Now, if your MCV is elevated, that's check for vitamin B12 and folate, that's usually the issue there. Finally, if your MCV is normal, you're anemic but your MCV is normal, this is where the provider's going to be wanting to look for things like sickle cell disease. Because in those conditions, the MCV can be normal, but you're just not making enough hemoglobin. So there's a whole host. The CBC is just a screening test. There's a whole host of normal lab tests, genetic lab tests that can be done to confirm the cause of the anemia.
Deandre White:
Are bone marrow biopsies ever necessary to come into that conclusion?
Dr. Kyle Riding:
Yes. In some cases...and it's very rare. It's very uncommon that a bone marrow biopsy is needed. But in some conditions, yes, a biopsy would be a necessity to diagnose the patient.
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