Chapter 4: Hematology

The content systematically addresses disorders affecting red blood cells, white blood cells, platelets, and coagulation mechanisms. Anemia represents a foundational concept, with classification into microcytic, normocytic, and macrocytic presentations based on mean corpuscular volume and underlying etiology. Iron deficiency, chronic disease processes, vitamin B12 insufficiency, and folate depletion constitute primary causative mechanisms, identified through complete blood count, peripheral blood smear analysis, reticulocyte enumeration, and targeted micronutrient assays. Hemoglobinopathies including sickle cell disease and thalassemia variants result from inherited structural or quantitative hemoglobin abnormalities, producing chronic hemolytic anemia and acute vaso-occlusive crises managed through supportive interventions, hydroxyurea therapy, and hematopoietic stem cell transplantation. White blood cell disorders encompass quantitative abnormalities and malignant transformations; acute and chronic leukemias present with distinct pathophysiological features, cytogenetic markers such as the Philadelphia chromosome in chronic myeloid leukemia, and treatment algorithms incorporating chemotherapy, targeted monoclonal antibodies, and stem cell transplantation. Lymphoproliferative disorders including Hodgkin and non-Hodgkin lymphomas and multiple myeloma require multimodal diagnostic approaches utilizing flow cytometry, bone marrow examination, and immunophenotyping. Platelet and coagulation disorders include immune-mediated and drug-induced thrombocytopenia, inherited deficiencies in coagulation factors as exemplified by hemophilia A and B, von Willebrand disease as the most prevalent inherited bleeding disorder, and acquired vitamin K-dependent factor insufficiency. Hypercoagulable states result from inherited thrombophilias including Factor V Leiden mutation and protein C and S deficiencies, or acquired conditions such as antiphospholipid syndrome, managed through anticoagulation with unfractionated heparin, warfarin, or novel direct oral anticoagulant agents. The chapter integrates diagnostic methodologies, pathophysiological mechanisms, and evidence-based therapeutic strategies applicable across clinical settings.