Chapter 62: Hematological Disorders

The framework for anemia evaluation requires determining whether the underlying problem stems from decreased erythrocyte production, impaired cell maturation, accelerated hemolysis, or acute hemorrhage. Microcytic anemias, characterized by reduced mean corpuscular volume, most frequently result from iron deficiency caused by inadequate dietary intake, malabsorption syndromes, or chronic bleeding sources, though thalassemias and sideroblastic disorders also fall within this category. Normocytic anemias typically develop in chronic inflammatory conditions or follow acute blood loss, with hemolytic mechanisms producing either fragmented or spherical red blood cells depending on whether hemolysis occurs intravascularly or extravascularly. Macrocytic anemias reflect disrupted deoxyribonucleic acid synthesis from cobalamin or folate insufficiency, with the critical distinction that cobalamin deficiency produces reversible neurological complications whereas folate deficiency does not. Sickle cell anemia, an inherited condition from a specific mutation in the beta-hemoglobin gene, generates pathological sickling of erythrocytes under low oxygen conditions, precipitating vaso-occlusive crises and progressive organ dysfunction. Polycythemia represents the opposite condition, involving elevated erythrocyte concentrations that increase blood viscosity, with distinctions made between relative forms from plasma volume contraction and absolute forms from primary myeloproliferative disease or secondary erythropoietin overproduction. The chapter also addresses leukemias as hematopoietic malignancies, categorized by cellular lineage and disease tempo, with acute forms requiring intensive multi-phase chemotherapy and chronic forms often managed through targeted molecular inhibitors or observation protocols. Throughout, emphasis is placed on the primary care provider's role in screening, establishing initial diagnoses, and coordinating long-term monitoring and patient education regarding treatment compliance and early recognition of complications.