Spherocytes

Spiros, ice literally means a circular cell. Normally, your red blood cell is a nice biconcave disk, but the spherocyte is abnormal. This is a sphere, a circle with no central pattern. It is small, and it is condensed. But the normal red blood cell, in a cross-section, has central pallor in the middle; the center is pale, just like a doughnut.

So, what's the difference between a normal red blood cell and a spherocyte? The normal red blood cell is biconcave; this one is circular. This has a larger surface area because of the folds of the biconcave shape; this has a smaller surface area because it's a condensed circle. This one has central pallor—if you see it at a cross-section, you'll see the center is pale. This has no central pallor. This one is biconcave, so it can maneuver through the splenic sinusoids; this cannot maneuver; it gets stuck, and maybe the splenic macrophage will consume it. This can expand in hypotonic solution, again because of the biconcave disk; this cannot expand in a hypotonic solution, so they will burst, and this will lead to hemolysis, which is never good. Don't forget: normal red blood cells have central pallor, like a doughnut; this one is like an apple pie.

Please pay close attention here, because many students confuse this. Just because you have spherocytes on your blood film doesn't necessarily mean that you have hereditary spherocytosis. This could be just hemolysis. Yes, that's true. When you see spherocytes on the blood film, this could be either hereditary spherocytosis or just hemolytic anemia. The majority of the cases are good old hemolytic anemia. Fine. We have talked about hereditary spherocytosis before; please go ahead and watch that video if you'd like. There, we had a loss of spectrin and ankyrin 3.1 proteins; the red blood cell could not maintain its shape and changed it into a sphere. In non-hereditary cases, such as hemolytic anemia, the macrophage is attacking the red blood cell, forming little blebs on the surface. Eventually, the red blood cell will become a sphere, called a spherocyte. Spherocytosis just means a state, a condition of spherocytes. So, when you have a lot of spherocytes in the blood, this is called spherocytosis. Most of the cases, it will be hemolytic anemia, not hereditary spherocytosis. If you ask, spherocytes in the umbilical cord—this is incompatibility, which causes hemolytic disease of the newborn; of course, this is hemolytic anemia.

Now, question: How about the Coombs test in case of hereditary spherocytosis? It will be negative. Why? Because in hereditary spherocytosis, the problem is genetic; there is no antigen-antibody reaction. However, in hemolytic anemia cases, like autoimmune hemolytic anemia, cold agglutinin disease, drug-induced hemolytic anemia, the Coombs test will be positive, of course.

Now, next question: How about splenectomy? Can splenectomy cure the spherocytosis? In case of hereditary spherocytosis, no. If you remove the spleen, the hemolysis will get cured, but the spherocytes will remain there. On the other hand, theoretically speaking, in case of hemolytic anemia, especially if there is splenomegaly and there is extravascular hemolysis, if you remove the spleen, maybe when these cells get destroyed after 120 days, the bone marrow will produce normal-shaped cells again—theoretically speaking.

Let's try to enter this vignette together. You have an 8-year-old boy brought by his mom because he feels tired all the time, which means maybe anemia. On physical exam, there's yellow sclera, maybe jaundice, pale face—anemia. They explained splenomegaly, which means maybe hemolytic anemia. Red blood cell count—how about this? This is low; hemoglobin, this is low; hematocrit, this is low. This means what? We have anemia. Reticulocyte count is high; this means hemolytic anemia with good bone marrow response. White blood cell—this is normal. Indirect bilirubin is high; okay, could be again hemolytic anemia. Blood film shows spherocytes—oh, this is a big deal—but the antiglobulin test, or the Coombs test, is negative, which means this is a hereditary spherocytosis and this is not autoimmune hemolytic anemia, for instance, because autoimmune hemolytic anemia will have a positive Coombs test. So, what's the most likely diagnosis? Of course, this is hereditary spherocytosis. Why not warm autoimmune hemolytic anemia? Because this will have a positive Coombs test. How about aplastic anemia? Now, aplastic anemia will have pancytopenia, but here the white blood cell count is normal.

Okay, next question: What should you do next? How about the sucrose hemolysis test? Okay, this is used in what? In paroxysmal nocturnal hemoglobinuria. As you know, the Schilling test is an archaic test for B12 deficiency. B12 deficiency will have neurological problems as well as maybe spherocytes, and also the indirect bilirubin will be normal. How about osmotic fragility test? Yes, this is the diagnosis, or the diagnostic test, of hereditary spherocytosis. See, medicine makes sense when you understand it. Thank you very much for watching. Please subscribe, and please follow me on Facebook. I'm posting many questions on my Facebook page, and I'll see you soon. Thank you.