Transcription
Hey, it's a new day. In your video, let's talk about hereditary elliptocytosis. In the last video, I mentioned hereditary spherocytosis. They are very similar, but not the same; symptoms of anemia or the same. This, like hereditary spherocytosis, is an intrinsic defect with extravascular hemolysis happening, i.e., the spleen. So what's the problem? Normally, your red blood cell is circular, biconcave, non-nucleated. Elliptocytes are elongated, not circular.
Here are the causes of normocytic anemia: acute blood loss, underproduction, or over destruction or hemolysis. Reticulocyte index in hemolysis will be greater than 2.5. The defect is either intrinsic or extrinsic to the red blood cell. Intrinsic defects include membrane defects such as spherocytosis. Hereditary elliptocytosis is also here; it's a membrane defect. The mechanisms of hemolysis are either intravascular or extravascular. Extravascular means reticulo-endothelial system: spleen, liver, or lymphocytes, but mainly the spleen.
Here is the mechanism of extravascular hemolysis. If you'd like some details, go to my video on extravascular hemolysis. The membrane of the red blood cell, as any membrane, is a lipid bilayer penetrated by proteins such as band 3. Also, we have other proteins anchoring, and we have bands; we have band 4.1. This is especially important in hereditary elliptocytosis and spectrin: alpha spectrin, beta spectrin, connected to ankyrin, tropomyosin, so that they contract and make this membrane flexible. So there is the cytoskeleton; there is the membrane. Normally, your red blood cell has a biconcave disc, and this has two main purposes. Number one, it can expand during osmosis when it pulls fluid from the outside environment. The normal red blood cell can expand, so it will not burst. Second, it can maneuver through these spleen sinusoids. Sinusoids are small capillaries; they have force. Normally, the red blood cell can squeeze itself because it's biconcave. This elliptocyte, it depends: if it goes to the sinusoid pore in this way, it will get stuck; if it goes through this way, it can pass. The normal red blood cell can change its shape, i.e., flexible. Elliptocytes are not flexible, so they can get stuck, and then macrophages come, and they will destroy them.
Hereditary elliptocytosis is an autosomal dominant problem. Usually, the patient is heterozygous, such as A a (uppercase, lowercase). So this is heterozygous because you only need one allele or one gene from the dominant to express itself. Can it be homozygous? Of course, it can, but it's lethal; that's very bad. Many genes are responsible for hereditary elliptocytosis. Family history of anemia or hemolysis could be because it's genetic. There is no correlation between elliptocyte morphology and the clinical severity, meaning that you can have 100% of your blood elliptocytes, and you have very little or no hemolysis. You can have a lot of elliptocytes, as well as normal cells, and still get severe hemolysis. So there is no correlation between the elliptocyte morphology and the clinical severity.
Pathophysiology: again, instant extravascular hemolysis. Case: these elliptocytes get stuck in the spleen, sometimes attacked by macrophages because they are elliptocytes, and they are stuck in the sinusoids. When they are destroyed, hemoglobin has heme and globin; protoporphyrin; unconjugated bilirubin goes to the liver; conjugated goes to the gallbladder; can precipitate as pigmented stones due to hemolysis, also thanks to calcium. Also, LDH can rise if hemolysis, or perhaps hemoglobin levels will be below. This is not always the case. Hereditary elliptocytosis can lead to hemolysis, so all of this will be true or cannot wait to hemolysis. So you will never see anything; the patient will be completely asymptomatic. So please keep this in mind. Again, the diagnosis only if severe; if the patient is asymptomatic, you will never know, except if you do blood tests.
Clinically: maybe anemia, jaundice, gallstones, feeling unwell, of course, because it's extravascular hemolysis; family history maybe. So hemoglobin: again, if the patient is normal, there is normal; if there is hemolysis, so we will have low hemoglobin, because it's anemia. MCV is usually normal; mean corpuscular hemoglobin concentration not important here; it's unique in spherocytosis, not elliptocytosis. Okay, Coombs test will be negative; bilirubin may rise; ultrasound may show gallstones; reticulocyte may rise if there is hemolysis. RDW: it depends; if 100% of the cells are the same, like elliptocytosis, it will be different; different shapes; different shapes raise the RDW. Peripheral smear, of course, will show elliptocytes. You can use all of these tests, but they are not important like elliptocytosis; it's very diagnostic by the peripheral smear. The band is not 3.1; it's 4.1 in elliptocytosis; 3.1 was spherocytosis; 4.1 elliptocytosis.
There is no cure yet for this genetic problem, but we can help. We can give folic acid; we can give folate and iron because bone marrow needs a lot of these nutrients and factors to build new RBCs because many of them are being destroyed in the spleen. Splenectomy, of course, but we wait until puberty before splenectomy. We get anti-pneumococcal vaccine because pneumococci are capsulated organisms, and we need the spleen for that. As splenectomy: after splenectomy, some doctors give penicillin; some doctors do not. This spleen will stop the hemolysis; it will never remove the elliptocytes, of course. If there are gallstones, this is very rare, but if there is or there are any gallstones, we will remove the gallbladder: cholecystectomy. And that's it for hereditary elliptocytosis. Pretty similar to spherocytosis; remember the difference is that the shape of the red blood cell is oval instead of the spheres in spherocytosis. The protein is band 4.1; hemolysis is more rare; usually it's autosomal dominant, and the patient is heterozygous. If there is hemolysis, then we do all of this; if there is no hemolysis, just leave them as they are; they are pretty good. That's all; see you in the next video.