Published on March 11, 2015
Dr. Susan Leclair answers the question “Why do we have red blood cells?” She delves into hemoglobin’s complex structure, its mechanisms and delivery system, and offers deeper insight into what you should know about haptoglobin and why your doctor checks it.
Transcript | Why Do We Have Red Blood Cells?
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All right. So we've talked a little bit about how red cells are made. Why do we have them in the first place? We have them in the first place, because we need to bring oxygen into the tissues. Now if we were two-celled sponges, we wouldn't have a problem with that, because either side is available and open to the air and can pick up oxygen, but we're not. We have—we have internal structures that need oxygen, so we need something that's going to get into those internal structures and deliver oxygen and take carbon dioxide away. So the red cell does that.
Well, not exactly. It's what's inside the red cell that's important. Hemoglobin is the reason you have red cells, and you have hemoglobin, because you need oxygen to get into the tissues. Hemoglobin is a very complex structure. There are different kinds of hemoglobins that occur as you grow and age and develop.
There are different kinds of hemoglobins depending upon whether or not there is oxygen attached to it or whether there's carbon dioxide attached to it, but essentially they all work the same way.
And probably the easiest way to think of the structure of hemoglobin--this is not going to get all that chemical—is to think of a ring that's got a single stone in it like this amethyst. Hemoglobin is composed of three things: a protein structure that protects and carries the active so think of that as the ring portion; something called protoporphyrin, which you can think of as the setting; and it holds and protects at the same time the iron molecule, which is the most important part of the hemoglobin, and that's the stone itself.
And what happens is you have four of these stuck together in a kind of a dance. And what happens to the hemoglobin molecule is when it needs oxygen it opens up, allowing those four iron molecules to pick up oxygen. And then it closes down to protect it, lets the oxygen go off into the tissues, closes down again, comes back to the lungs, picks up oxygen, gets rid of the oxygen, comes back to the lungs.
And in a way, if you watch this molecule work, it breathes, just the way you do. It opens up and allows oxygen to come in, it closes down after oxygen has been dispersed, and it keeps doing this, twisting and opening, to allow the iron to work. It's rather a beautiful dance that it does with oxygen.
It will take up four molecules of oxygen. It has four molecules of iron, which is the active part of hemoglobin. Let's say someone has an iron deficiency. Well, they're not going to have four molecules of iron available to the hemoglobin. Does that mean it couldn't have hemoglobin with three iron molecules? No.
What happens is the quality control of the body doesn't let that happen. You either have a functional hemoglobin with four iron molecules, or you don't have hemoglobin.
So one of the things you may have noticed on some of your reports or in your conversations with your physician is that if you have an iron deficiency—the single most common anemia in the world, especially for women, but you guys are involved in it as well—one of the things that they will tell you is that your hemoglobin is low. Your hemoglobin is low, because you don't have enough iron to make all the hemoglobin that you need.
Iron is not only found in hemoglobin, although maybe 90 to 95 percent of it is found in hemoglobin, it's in other things as well. It's in white cell enzymes. Why is that important?
Because you really want your white cells to defend you against bacteria, so you want them functional. You want all their enzymes to work, and if a couple of those enzymes need iron and don't have iron, well, then those white cells aren't going to be able to work as well as they should.
You need to have iron in the development of platelets, which we'll talk about later, but basically if you don't have enough iron you're going to make funny platelets. You're going to make platelets that are smaller than they should be, that don't work as well as they should be.
So iron is something that's found in lots of other cells besides red cells. It's just that the dominant amount of iron is so connected with hemoglobin we tend to forget that iron is found in other cells. I wanted you just to remember that, that when someone is talking about iron deficiency it's not just their hemoglobin that's involved. It's white cells and platelets and liver cells and skin cells and a lot of other cells that are also going to be impacted by this. Yes, the most important, the most noticeable is the red cell number in the hemoglobin, but it's not the only thing.
Hemoglobin inside a red cell is a wonderful thing to have. If you break a red cell (slams hand), I probably just broke a number of red cells. I probably also broke a couple of blood vessels, and clotting is happening in my hand at the moment, but right now I'm just interested in the red cells I just smashed.
The hemoglobin that's inside those red cells is now out in the peripheral blood—hemoglobin inside a red cell, a miracle of nature. Hemoglobin outside in the peripheral blood can shut down your kidneys. It's highly toxic, so I need something right now to get to the area that has that free hemoglobin and do something with it to make it less toxic.
One writer wrote in and asked what is haptoglobin, and why is it Important? There's a compound your liver makes called haptoglobin. It binds to free hemoglobin, so it's constantly wandering around your bloodstream looking for free hemoglobin to clean up. When it binds to hemoglobin the first thing that happens is, I'm lucky, all my free hemoglobin has now been bound to my haptoglobin. So my kidneys don't have to worry, and all of that bound haptoglobin/hemoglobin is going to go over to my liver to be completely broken down and detoxified.
That means if I analyze for the presence of haptoglobin in me, right now I don't have as much free hemoglobin—free haptoglobin in me as I did before I hit my hand against the chair. It's lowered. I'm only measuring free hemoglobin, free haptoglobin. I don't measure haptoglobin that's bound to hemoglobin. So if I have excess free hemoglobin out in my peripheral blood, my hemoglobin—my haptoglobin is going to drop.
And when my haptoglobin drops, it is a sign to the physician that maybe what's going on is that there's increased red cell death going on in the peripheral blood, maybe because I'm klutzy and I keep banging chairs or banging into them. So those of you who have got a lot of bruising right now, look around and recognize the fact that your haptoglobin is probably a little on the low side.
Or something else is going on inside your blood vessels that's causing these cells to die earlier and inappropriately. You want them to die in the spleen, because everything gets taken care of beautifully in the spleen. If they're broken out in the blood vessels, that's when haptoglobin is needed. They shouldn't be breaking out there in large numbers, so some kind of hemolytic process is going on. I don't what. I don't for how long. I don't even know where, but I know that it's happening if my haptoglobin is dropping.
Next time, we'll talk about how some of this stuff feeds into the concept of anemia. Meanwhile, remember, send questions to email@example.com, and knowledge can help you a lot when you're dealing with physicians. It's one of your most powerful tools. See you later.