Chapter 33: Hematologic System Assessment

The hematologic system encompasses bone marrow, blood components, spleen, lymphatic structures, and liver, functioning collectively to transport oxygen and nutrients, maintain hemostasis, and provide immune defense. Hematopoiesis occurs in bone marrow under regulation of growth factors including erythropoietin and colony-stimulating factors, producing erythrocytes for oxygen transport, leukocytes including granulocytes and lymphocytes for immune function, and platelets derived from megakaryocytes for clot formation. The chapter details hemostatic mechanisms involving vascular response, platelet aggregation, coagulation cascade activation, and fibrinolysis for clot dissolution. Iron metabolism is explored through absorption, transport via transferrin, and storage as ferritin, with disruptions leading to deficiency or overload conditions. Age-related changes include decreased bone marrow mass, reduced erythropoietin response, and compromised immune function, predisposing older adults to anemia and infection. Clinical assessment integrates comprehensive history-taking focusing on bleeding tendencies, fatigue, medication effects, and family history with systematic physical examination for pallor, petechiae, lymphadenopathy, and hepatosplenomegaly. Diagnostic evaluation encompasses complete blood counts with differential analysis, coagulation studies including prothrombin time and partial thromboplastin time, iron studies measuring ferritin and transferrin saturation, vitamin assessments for folate and cobalamin levels, and advanced procedures such as bone marrow biopsy and flow cytometry for hematologic malignancy detection and characterization.