The document discusses anemia classification and investigation tests. It provides definitions and classifications of anemia based on red blood cell count, hemoglobin, and hematocrit levels. The main types of anemia are outlined as blood loss, deficient red blood cell production, and excessive red blood cell destruction. A complete blood count, blood film, iron tests, and bone marrow examination are important tests to evaluate the cause of anemia. The reticulocyte count helps indicate whether the bone marrow is responding to the anemia.