Transcription
Hey guys, it's Medicosis Perfection Analyst. Let's go on continuing our series about bleeding and coagulation disorders.
In the previous videos, we have talked about platelets and their structure, the arachidonic acid, and thrombocytosis. Today, I'll talk about thrombocytopenia. Pina means decreased, cyto means cell, thrombo means the thrombosites or the platelets. Theoretically, thrombocytopenia is less than 150,000, but clinically, we as doctors couldn't care less about your platelet count until they go below 50,000. So let's get started. [Music]
So here are my previous videos in this series; it's called Bleeding and Coagulation. Make sure to subscribe and save this playlist. There is a button called "save"; you just save it, and boom, it's in your channel. Normal platelet count is 150,000 to 400,000 per microliter. We don't care about thrombocytopenia unless it's less than 50,000. We don't care about thrombocytosis unless it's more than 750,000, and it has to do with the normal distribution curve. Here is 150,000 all the way until 400,000. If you are 120,000 here without any symptoms, you are nothing beside to panic; it's just like the normal distribution of the frickin' curve. Same thing, if you are 500,000 platelets, doesn't mean that you have thrombocytosis and you're gonna throw 'em both to death; no, it's just normal.
We start with the pluripotent stem cells, not the multi—the pluripotent stem cells. Myeloid might give us megakaryocytes, and then the platelets. Platelets are not cells; they are just pieces of the megakaryocyte. Thrombocytes—the cells of thrombosis. Decreased number called thrombocytopenia; increased number called thrombocytosis or thrombocythemia. Quick review of the previous video: we had thrombocytosis. We had two types of thrombocytosis: primary or essential, part of the myeloproliferative neoplasm; and secondary, which is the most common. It's secondary to another disease. Hard percent of cases in kids is secondary; a percent of cases in adults is secondary. Here, thrombocytopenia is decreased platelet count, theoretically less than 150,000; clinically less than 50,000.
Causes: we have two types; we have the pseudo thrombocytopenia—this furious type. It's an artifact. Again, don't trust the stupid machine. And the true thrombocytopenia. True thrombocytopenia has three different causes. Remember anemia? We had anemia of underproduction and anemia of overdestruction. Same thing here. Thrombosis—underproduction, overdestruction, and splenic sequestration because one-third of the platelet pool is hiding inside the spleen. So as the spleen enlarges, it can destroy more platelets, decreasing the platelet count in the peripherals. Near the pseudo—the fake thrombocytopenia—it's an artifact. We collect blood in a test tube. If the top is purple, it means that it has an anticoagulant in it. By the way, in the lab, they called the lavender tube. When I first came to the United States, I didn't know what the frick is lavender, and all the lab technicians started making fun of me. And then I discovered that lavender is the same as purple; it came from a flower called Lavandula. And then I became an expert about lavender, and that's why I make fun of lab technicians in my videos all the time. Never make a Medicosis angry; just kidding.
So when the test tube has EDTA as an anticoagulant to reduce calcium and prevent clotting, because calcium—coagulation, also calcium—contraction of platelets and release of granules. When it has EDTA, there is a problem. When the test tube has EDTA, sometimes you have antibodies against them, called IgG. They bind to the platelets, and they form this kind of rosette formation, this satellite formation. This satellite formation leads to platelet agglutination, but the machine is stupid; it counts this body as only one platelet instead of like what, seven platelets. So that's why it's called the analyzer; it's a stupid, but machine. How to prevent the pseudo thrombocytopenia? Use a different test tube; use the green one, use the blue one. The blue one has sodium citrate; the green one has heparin. It's heparinized, so they won't include this EDTA. By the way, it doesn't have to be EDTA; any other anticoagulant can cause the same problem. Or non-physiologic cold agglutinin at room temperature again can cause the same pseudo thrombocytopenia. Another way to prevent pseudo thrombocytopenia is to do a peripheral smear, and you will see the platelet clumping. Then that you will realize, okay, now I have a patient who is asymptomatic; his platelet count is low because that machine is a stupid, but machine. However, when I look under the peripheral smear, I see the platelets clumping together. So this is pseudo thrombocytopenia. Okay, I wanna make sure you can use a different test tube, and now the platelet count should be normal.
True thrombocytopenia—now we're talking. It's either underproduction, overdestruction, or splenic sequestration. Underproduction could be inherited or acquired, such as aplastic anemia, which is a wrong name; should be aplastic pancytopenia. Myelodysplastic syndrome—again, disease of the bone marrow. Platelets are coming from the bone marrow; makes perfect sense. Liver disease, because the liver secretes the thrombopoietin. When you have liver disease, you have decreased thrombopoietin. Dehydration, decreased B12 and folate, because B12 and folate are important for synthesis of nucleus, and since the megakaryocytes have nucleus too, so they need B12 and folate. Fanconi anemia, because Fanconi anemia is an aplastic anemia—I'm sorry—aplastic pancytopenia. And Bernard-Soulier disease. Which—and let's go to the overdestruction. It's either immune or non-immune, such as immune thrombocytopenic purpura, disseminated intravascular coagulopathy, thrombotic thrombocytopenic purpura, hemolytic uremic syndrome, HELLP syndrome, which is hemolysis, elevated liver enzymes, and low platelets, which means thrombocytopenia. Systemic lupus erythematosus and antiphospholipid antibody syndrome.
Next, we have the splenic sequestration. Hypersplenism—when the spleen is large or is hyperfunctioning, it will hide more platelets; it will engulf more platelets in it. Also portal hypertension, because portal hypertension will lead to splenomegaly. Same thing; this is called splenic sequestration. There are the—there is another cause called medication-induced. How does the medication-induced thrombocytopenia? By damaging the bone marrow, called myelosuppression, such as valproic acid, chemotherapy, methotrexate, and fludarabine. If you ask a pharmacologist, he will give you a very big way that can wrap around the planet Earth twice. Clinically speaking, many cases are asymptomatic, or they can have symptoms such as superficial bleeding. Platelet problem—have superficial bleeding. Coagulation factor problem—we'll have hemarthrosis, which likes bleeding into joint; that's a very deep bleeding, as well as late rebleeding. So, for example, you remove a tooth, and the dentist is happy because you didn't bleed much, and hey, go home. You go home several hours later; you bleed to death; you literally choke on your own blood. That's how severe and deep of a bleeding hemophilia is. Let's go to the superficial bleeding due to a platelet problem. It's either skin bleeding or mucosal bleeding. Skin bleeding such as petechiae, which is—which is very small, 1 to 2 millimeters. Larger are called ecchymosis, more than 3 millimeters. And the largest of the large is called the purpura, more than 1 centimeter. Mucosal bleeding—epistaxis is the—it's very common; alternate as nosebleed. Most epistaxis are coming from the Kiesselbach's triangle. Bleeding from superficial scratches, as a pinprick or a paper cut. Easy bruising, menorrhagia, excessive menses, GI bleeding, hemoptysis, hematuria. And really severe, you can end up with intracranial hemorrhage. But no late rebleeding and no hemarthrosis; these are coagulation factor deficiency. So these are primary hemostasis problems; these are secondary hemostasis problems.
Treatment: no symptoms, no treatment. But shouldn't we treat the patient just because they have a low platelet count? Shut up! Hippocrates said, "Do no harm." Over-treatment is also bad. Under-treatment? Yeah, of course, it's bad. Both of them are bad. Do no harm. The patient's asymptomatic; don't waste resources and don't make the patient's life worse. Treat the underlying cause. Steroids and folate to boost platelet production. Transfusion of fresh platelets therapeutically for severely symptomatic patients. Because if you have a patient who has like 60,000 or 50,000 platelet count and he is mildly—mildly symptomatic, just small little bitty petechiae, and you transfused fresh platelets, you're an idiot. Because let's say that you don't have enough fresh platelets at the hospital; you gave them all to this mildly symptomatic person. Then at the same night came several people who need fresh platelet transfusion; you'll tell them, "Oh, I'm sorry, I just gave—I gave all of my platelets to this moderately symptomatic PTA patient, and I'll just leave you bleed to death." You'll be an idiot, and you'll lose your license. Only use fresh platelets for severely symptomatic patients or prophylactically for platelet count less than 10,000, which is probably gonna be very bad soon, so you better give fresh platelets now. Splenectomy is last resort, since platelets are hiding in this spleen; removing this spleen will force all of the platelets outside and back to the bloodstream, raising the platelet count back to normal, but it's last resort because spleen is like an immune organ; spleen is important for the immunity, especially in young kids.
Clinical take-home points: thrombocytopenia relevant only if the platelet is less than 15,000. Patients with thrombocytopenia have increased risk of superficial—superficial bleeding. Thrombocytopenia can lead to retinal microvascular pothi; it can lead to bruising. Aggravate if the patient already has vitamin C deficiency, which is known as scurvy, because scurvy will make your blood vessel wall very weak. You have weak blood vessel wall and low numbers platelets, you'll end up with bad bruising. Same thing with alcoholic and malnourished patients; they have weak vessels, and when they have low platelets, the bruising is going to be worse. Thrombocytopenia can occur after lumbar puncture, and they can lead to spinal hematoma. Autoimmune hemolytic anemia and autoimmune thrombocytopenia in the same patient at the same time is called Evans syndrome. During pregnancy, you may get thrombocytopenia. Why? It could be benign—benign gestational thrombocytopenia. Why? It's dilution; the plasma level increased; plasma volume increased like crazy. Now the platelets are diluted because relative to the plasma, we have now fewer platelets. This is called dilutional thrombocytopenia. Also, they get dilutional anemia. Or the thrombocytopenia could be pathological, such as ITP, TTP, preeclampsia, DIC. So thrombocytopenia is a very important thing in pregnant women.
Let's put it all together. Thrombocytopenia is decreased platelet count; theoretically, as your professor might prefer, less than 150,000. Less than 90,000, bleeding time starts to prolong. Less than 50,000, you will get the clinical picture, signs and symptoms. Less than 30,000, many patients will get spontaneous bruising. Less than 20,000, many patients will get severe bleeding. Less than 10,000, please transfuse platelets prophylactically even without symptoms. Less than 5,000, extremely severe bleeding and spontaneous hemorrhage. How about major invasive surgery? You're preparing the patient for a major surgery, and you are worried about his platelet count. If the platelet count is greater than 50,000, go ahead and do the surgery, provided that everything else is normal. Talk to your surgeon.
Quiz time: you have a new patient who is asymptomatic and perfectly fine. You order some labs; discovered thrombocytopenia; his platelet count is really low. Question is, what's the next best step in management? Let me know in the comment section, and the answer will be in the next video. Thank you so much for watching. You can get more notes by going to patreon.com/Medicosis. Don't forget to subscribe and join the Facebook group to get many cases, and you'll get all of my notes in a Dropbox link if you go to Patreon. Thanks for watching. As always, be safe, stay happy, and study hard and smash like!