What is anemia?
Anemia is a condition that occurs when your blood has a lower-than-normal amount of red blood cells or hemoglobin. It is a decrease in RBC count, hemoglobin, or hematocrit values that lowers the ability for the blood to carry oxygen to body tissues. This leads to hypoxia and hypoxia-induced effects on organ function. Results in the signs and symptoms of anemia. Let's look at the classification on the basis of reticulocyte count. A low reticulocyte index of less than 2.5 makes it hypoproliferative anemia. Next is a high reticulocyte index greater than 2.5 index termed hyperproliferative anemia. There are two types of hyperproliferative anemia: anemia due to blood loss and hemolytic anemia. Hypoproliferative anemia is divided into three types: microcytic anemia, normocyctic anemia, or macrocytic anemia. In microcytic anemia, you have MCV < 80 fl. In normocytic anemia, MCV is between 80-100 fl. In macrocytic anemia, MCV is > 100 fl.
In microcytic anemia, red blood cells appear smaller and paler than normal. Typical causes of microcytic anemia are iron deficiency, anemia of chronic diseases, thalessemia, sideroblastic anemia, and hemoglobin E. In normocytic anemia, all the parameters of red blood cells are normal. Mean corpuscular volume is always less than normal. This anemia is caused by renal failure, anemia of chronic diseases, hypothyroidism, aplastic anemia, or acute blood loss. In macrocytic anemia, bone marrow produces MCV > 100. This anemia is caused by vit B12 deficiency, folate deficiency, hypothyroidism, myelodysplastic syndrome, or alcoholic liver disease.
Further classification based on clinical features, are below: Iron deficiency anemia is where there is an excess loss of iron. Megablastic anemia is where there is less intake of vitamin B12 and folic acid. Pernicious anemia is where there is malabsorption of vitamin B12. Hemorrhagic anemia which is due to the excess loss of red blood cells. Hemolytic anemia is where there is an abnormal destruction of red blood cells. Aplastic anemia is due to destruction of red bone marrow.
What are the causes of anemia? Loss of blood volume, acute hemorrhage gastrointestinal bleeding, increased destruction of red blood cells, auto-immune hemolytic reaction, iron deficiency related, chronic diseases, HIV, and heavy menstruation (or menorrhagia) are among several causes of anemia.
If you prefer a video over the notes, click the link below.