Transcription
Hey everybody. In the previous video, we discussed immune hemolytic anemia. Today, we'll talk about autoimmune hemolytic anemia, and there are two different subtypes, or, and called. Today, we'll discuss the warm and leave the cold for the next video.
Immune hemolytic anemia, as you know, is extrinsic or extracorpuscular; it could be either intravascular or extravascular. We have three different subtypes. Go-to immune hemolysis is by far the most common. It's a type 2 hypersensitivity reaction, could be with IgG or IgM. Today's topic is IgG, or the warm subtype.
As a general rule, when we talk about go-to immune disease, we have two types: either organ-specific or multi-system. Okay. Autoimmune hemolytic anemia is organ-specific because it affects only the red blood cells. This is organ-specific—only one organ or one system, okay, localized antigens. However, multi-system is immune response against widespread target antigens. A good example of this will be lupus. So, autoantibodies have two different choices: they can fix the complement avidly. When they fix the complements avidly, it's an intravascular hemolysis. However, if the complement activation is weak, it's an extravascular hemolysis. So, warm autoantibodies—80% of the cases—IgG, mostly against Rh antigens, called antibodies. Twenty percent of the cases—IgM—binds the complement usually avidly, so it's an intravascular hemolysis. To remember which is which: draw IgG inside the sun. IgG is warm, and IgM is a pentamer, which looks like a snowflake.
Warm autoimmune hemolysis—IgG represents 80% of the cases of autoimmune hemolytic anemia, more common in middle-aged females, and there's a mnemonic for that. With all due respect, IgG, to antibodies. Rarely is IgE or IgA. They can be primary or idiopathic, which means we are idiots because we don't know the pathology. Secondary, such as new connective tissue disease, as lupus, HIV, or viral vaccines, drugs such as cefoxitin, ceftriaxone. The Paris EMA optima hemolytic anemia is associated with primary sclerosing cholangitis. As a general rule in medicine, autoimmune diseases come with each other. So, when you have a patient with one certain autoimmune disease, he is more likely, or she is more likely, to have another autoimmune disease at the same time. Both immune diseases are associated with each other.
Pathophysiology is quite simple: you have your nice red blood cell getting coated with IgG. The macrophage would recognize the Fc portion on the IgG using the macrophages Fc receptor in the spleen. So, therefore, extravascular hemolysis. As you know, and we have discussed before, the extravascular hemolysis—of course, you know all of this stuff. Clinically, same signs and symptoms of extravascular hemolysis, but they aren't dramatic. So, we have massive splenomegaly, we have a rapid drop of hemoglobin, and all of the other symptoms. Autoimmune hemolysis has a triad of rapid drop of hemoglobin—remember, dramatic—jaundice, and splenomegaly, which is usually massive—again, dramatic. When noted, immune hemolytic anemia is associated with autoimmune thrombocytopenia at the same time. We call this Evans syndrome. Again, remember, autoimmune diseases come with each other.
How to diagnose autoimmune hemolysis: the clinical trial plus some investigation. The CBC will show you: hemoglobin will be low, hematocrit will be low. How about the reticulocyte count? It will be high because it's hemolysis, and usually this will lead to normal to high MCV because reticulocytes are bigger than the red blood cells. LDH will be high, unconjugated bilirubin will be high, haptoglobin will be low. Remember our discussion about hemolysis. The gold standard here is the direct Coombs test. We will talk about Coombs tests later, but remember, the direct Coombs test is the gold standard, and it's also known as the direct antiglobulin test. After diagnosed hemolytic anemia, please look for other diseases such as lupus or CL. Blood film will show spherocytes. This is different from hereditary spherocytosis. Having spherocytes alone does not mean that this is a hereditary spherocytosis; it could be also hemolysis, such as this case, because you have a red blood cell which is microcytic. You start to bite serbs and parts from the edges, converting this biconcave shape into a sphere—spherocyte.
Treatment: autoimmune hemolytic is dramatic. So, severe cases are medical emergencies and require blood transfusion. Pay attention, please: if the antibodies are not specific, you're better off transfusing incompatible blood. Now let's walk through this. Usually, when you give blood to a patient, we cross-match the blood to make sure that the donor blood and the recipient blood match. So, if the blood is compatible, and you give this blood to a recipient who has autoimmune hemolysis, which means autoantibodies in the blood, they will destroy the entire blood unit that you give them. If you give the patient one unit, they will destroy the entire red blood cells in that unit, which is so bad. On the other hand, if you give incompatible blood, the patient has—let's say 50% of the blood is okay—he will destroy 50% of the blood cells in the blood unit. So, this is better than destroying 100%; 50% is still better. That's why, probably, you should give incompatible blood only to patients with autoimmune hemolysis, and of course, this is extremely controversial. When the lab results improve, stop the blood transfusion and go to medical treatment: prednisone. Why prednisone? It's anti-inflammatory, and the process of macrophages destroying your red blood cell coated with IgG—this is probably inflammation—so prednisone can help, right? Rituximab is a monoclonal antibody against CD20. Splenectomy will help because this occurs in the spleen, so please, you can remove the spleen. Last resort: imagine we do a stem cell transplant.
Here is a question for you: a 71-year-old male with shortness of breath, feeling tired all the time. On exam, there is a heart murmur, five lateral axillary lymphadenopathy, and these lymph nodes are not painful on palpation. There is hepatomegaly, and they explain the stool blood test came back negative. On lab investigations, you have an MCV of 100, P-Mcvlog of 7.1, reticulocyte count of 8 percent, white blood cells of 23,000, platelets around 250,000. What's the next step? Give rituximab, give high-dose corticosteroids, or perform a splenectomy? Let me know in the comment or go to my Facebook page where I will post the answer. See you then.