Hematology Reviewer PDF

Hematology Reviewer This reviewer covers the essential concepts in hematology, including blood components, blood cell production, blood disorders, and diagnostic procedures. I. Overview of Hematology Hematology is the study of blood, blood-forming organs, and blood disorders. It is vital for diag...

Hematology Reviewer This reviewer covers the essential concepts in hematology, including blood components, blood cell production, blood disorders, and diagnostic procedures. I. Overview of Hematology Hematology is the study of blood, blood-forming organs, and blood disorders. It is vital for diagnosing, treating, and managing diseases related to blood and the immune system. II. Components of Blood 1. Plasma Makes up 55% of blood volume. A uid that transports nutrients, hormones, proteins, and waste products. 2. Red Blood Cells (RBCs) Also called erythrocytes. Contain hemoglobin, which carries oxygen from the lungs to tissues and removes carbon dioxide. 3. White Blood Cells (WBCs) Also called leukocytes. Defend the body against infections and play a role in immunity. Types: Neutrophils, Lymphocytes, Monocytes, Eosinophils, and Basophils. 4. Platelets (Thrombocytes) Cell fragments that help in blood clotting to prevent bleeding. III. Hematopoiesis (Blood Cell Formation) Hematopoiesis is the process of forming new blood cells. In fetuses, it occurs in the liver and spleen, while in adults, it primarily occurs in the bone marrow. Blood Cell Lineages: Myeloid Lineage: Produces RBCs, platelets, monocytes, and granulocytes (neutrophils, eosinophils, basophils). Lymphoid Lineage: Produces B cells, T cells, and natural killer (NK) cells. IV. Complete Blood Count (CBC) Parameters 1. Red Blood Cell Count (RBC) – Indicates oxygen-carrying capacity. Low levels suggest anemia, while high levels suggest polycythemia. 2. Hemoglobin (Hb) – Measures the oxygen-carrying protein in RBCs. Low levels indicate anemia. 3. Hematocrit (Hct) – Percentage of RBCs in blood. Low in anemia and high in dehydration. 4. White Blood Cell Count (WBC) – Re ects immune function. High levels may indicate infection, while low levels may fl fl suggest immune suppression. 5. Platelet Count – Evaluates clotting ability. Low levels (thrombocytopenia) increase bleeding risk, and high levels (thrombocytosis) may cause clotting. V. Common Blood Disorders 1. Anemia A condition where RBCs or hemoglobin levels are low. Causes include iron de ciency, vitamin B12 de ciency, and blood loss. Symptoms: Fatigue, pale skin, shortness of breath. 2. Leukemia Cancer of white blood cells leading to uncontrolled WBC production. Can be acute or chronic. 3. Thrombocytopenia Low platelet count, leading to easy bruising and bleeding. 4. Polycythemia Excess production of RBCs, increasing blood thickness and risk of clotting. 5. Hemophilia A genetic disorder where blood does not clot properly due to missing clotting factors. VI. Diagnostic Procedures in Hematology 1. Peripheral Blood Smear – Examines the size, shape, and number of blood cells under a microscope to detect abnormalities. 2. Bone Marrow Aspiration and Biopsy – Used to diagnose blood cancers and bone marrow disorders. 3. Coagulation Tests – Evaluate the blood’s ability to clot, including tests like Prothrombin Time (PT) and Activated Partial Thromboplastin Time (aPTT). 4. Reticulocyte Count – Measures immature RBCs to assess bone marrow activity. VII. Blood Cell Morphology Abnormalities Microcytic RBCs: Small RBCs, commonly seen in iron de ciency anemia. Macrocytic RBCs: Large RBCs, often due to vitamin B12 or folate de ciency. Hypochromic RBCs: Pale RBCs due to low hemoglobin. Sickle Cells: Crescent-shaped RBCs in sickle cell anemia. fi fi fi  Acanthocytes: Spiky RBCs, seen in liver disease. Teardrop Cells: Seen in bone marrow disorders like myelo brosis. VIII. Hemostasis and Coagulation Hemostasis is the process that stops bleeding, involving blood vessel constriction, platelet plug formation, and clot formation. Coagulation Cascade is a series of steps involving clotting factors that lead to the formation of a blood clot. Intrinsic Pathway: Activated by internal damage to blood vessels. Extrinsic Pathway: Activated by external trauma. Both pathways converge into the Common Pathway, resulting in brin clot formation. IX. Blood Typing and Compatibility ABO Blood Group System: Based on the presence of A and B antigens on RBCs. Type A: A antigen, anti-B antibodies. Type B: B antigen, anti-A antibodies. Type AB: A and B antigens, no antibodies (universal recipient). Type O: No antigens, both anti-A and anti-B antibodies (universal donor). Rh Factor: Positive (+) or negative (−) based on the presence of the Rh antigen. Rh incompatibility can cause hemolytic disease in newborns. X. Bone Marrow and Special Conditions Bone marrow produces blood cells, and its cellular composition can change in diseases. Hypercellular marrow: Seen in leukemia due to excessive cell production. Hypocellular marrow: Seen in aplastic anemia due to reduced production. Bone Marrow Cell Stages Myeloblast → Promyelocyte → Myelocyte → Metamyelocyte → Band cell → Mature granulocyte Variations in the percentages of these stages can indicate infections, cancers, or marrow failure. XI. Key Points to Remember Blood is composed of plasma, RBCs, WBCs, and platelets, each with distinct roles. Hematopoiesis in adults occurs mainly in the bone marrow. Anemia, leukemia, and clotting disorders are common blood-related diseases. CBC and peripheral blood smears are basic but vital diagnostic tools. The coagulation cascade is essential for proper blood clotting. Understanding blood types is crucial for safe transfusions. fi fi