 look at some red blood cell pathologies. There are several different types of issues that can go on with the red blood cells, but some of the most high yield are the following. We have Draco sites which are teardrop cells. We see that here in this picture. What this is is the blood cell is trying to squeeze out of the bone marrow that has fibrosis and something like myelofibrosis and that creates that teardrop shape of the cell. Next we have schistocytes which are also known as helmet cells and you can see that here in this picture in the few places here that I'm circling. These all look like helmets and what this is is a hemolytic anemia. Typically we see this in DIC. We also see this in TTP which is thrombotic thrombocytopenic purpura as well as in hemolytic uremic syndrome, HUS, and then we also find it in help syndrome and help is an acronym for hemolysis, elevated liver enzymes and low platelets. Typically we see that in preeclampsia and eclampsia. Furthermore the degma site is also known as a bite cell as you can see here with the arrow. Looks like something has come in and taken a bite out of that red blood cell. We see this very often in G6PD deficiency. Moving along we have spherocytes. Spherocytes are seen as a dark red blood cell with no central pallor so it doesn't have that biconcave shape of our normal red blood cells. This is seen in hereditary spherocytosis so you don't have that normal indentation of the red blood cell that increases the surface area and you can also see it in autoimmune hemolytic anemia. Next we have target cells and what you're seeing here is actually an additional surface area like here and it looks like you have a target. This is found often in alpha and beta thalassemias as well as hemoglobin C. You see it in iron deficiency anemia and it also comes in after a splenectomy because the spleen does a lot of the breaking down of the old red blood cells. Finally we have sickle cell that is very often seen in African Americans. These are a sickle shape to the cell here and we'll talk about that more here just now. So what is sickle cell anemia? Sickle cell anemia specifically is a point mutation with glutamic acid being replaced by valine. This is exacerbated when you have a low oxygen level high altitude or acidosis. So a common application of this is an athlete that goes to a high elevation to play in sports and if they have sickle cell they can actually exacerbate those symptoms and cause problems. So a lot of times you'll see athletes that will refuse to travel to elevated areas and play sports because of this issue because they will be seeing low oxygen level they'll be in a high altitude and that acidosis from playing those sports is a ticking time bomb for those athletes. So let's look and see what actually happens with sickle cell. So normally these red blood cells travel down the blood vessels and the blood cells here you can see tend to change their shape when they get to small blood vessels and capillaries. With sickle cell however these sickle cells do not change their shape and you find that they will start to occlude vessels as they try and travel into smaller areas. This is where you can get a vascular occlusive crisis. So our complications you can have an auto splenectomy and then beyond that have secondary infections with encapsulated bacteria like strep pneumonia. As I just mentioned you can have a vascular occlusive crisis where there's a lot of pain specifically in distal parts of the body where you see small capillaries and those sickle cells are getting stuck and causing a lack of oxygen to those distal tissues. We also can see salmonella osteomyelitis once again because of encapsulated bacteria. To treat this obviously is to do our best to not exacerbate these symptoms as far as the low oxygen high altitude and acidosis level but you can also treat it with hydration and then hydroxyurea. Hydroxyurea is used because it increases fetal hemoglobin. Fetal hemoglobin is not affected by sickle and sickling of the cells so if we increase the fetal hemoglobin we can decrease the effects of the sickle cells. Furthermore we have many different types of anemias that can occur an anemia is a lowering of the red blood cells in the body. There are three types of anemias three major types of anemias and that is microcytic where our mean corpuscular volume is less than 80. The mean corpuscular volume is basically the size of the red blood cell. You have a normalcytic anemia where you see a normal size of the red blood cells where their mcv is between 80 and 100 and then we have macrocytic anemia where that mcv is greater than 100. Let's talk about each individual one here a little bit closer. With microcytic anemias where you have that mcv less than 80 that's commonly seen in anemia of chronic disease. In iron deficiency anemia we see it in lead poisoning and then in thalassemias that's going to be alpha and beta thalassemias here. Moving on to normalcytic normalcytic is actually broken down into two further groups. It is in non-hemolytic anemias which where you see a low reticulocyte index and then a hemolytic normalcytic anemia where you have an elevated reticulocyte index. Let's discuss the reticulocyte index. This is a calculation that shows whether or not there are immature red blood cells that are present in the blood due to a decrease in the red blood cell amount currently in the blood. So if your body loses blood the reticulocytes will be released early before they are actually matured into erythrocytes and we can see that in a blood smear. So in a non-hemolytic anemia where we see a low or a normal reticulocyte index this is due to early iron deficiency. So right at the beginning of that iron deficiency everything seems to look normal from a blood sphere perspective besides having a decreased red blood cell count. You see anemia of chronic disease, aplastic anemia, and chronic kidney disease all cause a normalcytic non-hemolytic anemia. The hemolytic anemia can be then further broken down into intrinsic and extrinsic. So intrinsic hemolytic anemias are something that is only present due to something already within the body. So we see hereditary spherocytosis, paroxysmal nocturnal hemoglobin urea, G6PD deficiency, pyruvate kinase deficiency, sickle cell anemia, and HBC disease. We see the hemoglobin levels being decreased and the red blood cell size remain normal. With extrinsic hemolytic normalcytic anemia that is often seen on something that is outside of the normal functions of the body. So an autoimmune disease, micro angiopathic or macro angiopathic diseases, and infections can all cause an extrinsic hemolytic normalcytic anemia. Moving on to macrocytic anemia, this is broken down into two different types. You have megaloblastic and non-megaloblastic. The megaloblastic is due to failure of DNA synthesis and the preservation of RNA synthesis, which gives us a restricted cell division in the progenitor cells. So what you're really seeing with megaloblastic anemia is hypersegmented neutrophils. Those hypersegmented neutrophils will help you establish a megaloblastic versus non-megaloblastic macrocytic anemia. Megaloblastic is caused by folate deficiency, vitamin B12 deficiency, orthotic aciduria, and fancones anemia. And in non-megaloblastic anemia, that's often caused by diamond black fan anemia, liver disease, and alcoholism. We'll talk more about each one of these types of anemias later.