Hematologic System Assessment | Chapter 33 – Lewis’s Medical-Surgical Nursing (12th)

Описание: Chapter 33 of Lewis’s Medical-Surgical Nursing (12th Edition) provides an in-depth review of the hematologic system, including its structures, functions, assessment techniques, age-related changes, and diagnostic studies essential for clinical nursing practice.

The hematologic system is responsible for oxygen and nutrient transport, waste removal, fluid and electrolyte balance, acid-base homeostasis, hemostasis, and infection defense. Core structures include the bone marrow, blood, spleen, lymphatic system, and liver. Bone marrow produces all blood cells through hematopoiesis, regulated by growth factors such as erythropoietin, thrombopoietin, and colony-stimulating factors. Blood is composed of plasma (water, proteins, solutes) and formed elements:

Erythrocytes (RBCs): carry O₂/CO₂ via hemoglobin, maintain acid-base balance, and are regulated by erythropoiesis.

Leukocytes (WBCs): include granulocytes (neutrophils, eosinophils, basophils), lymphocytes (T cells, B cells, NK cells), and monocytes/macrophages, providing immunity and phagocytosis.

Platelets (thrombocytes): derived from megakaryocytes, initiate clot formation and stabilize hemostasis.

The spleen filters old RBCs, stores platelets, and contributes to immune defense. The lymphatic system returns interstitial fluid to circulation, transports fats and proteins, and filters pathogens. The liver synthesizes clotting factors, regulates iron metabolism, and produces hepcidin to maintain iron balance.

Hemostasis is detailed as a multi-step process involving vascular response, platelet adhesion/aggregation, clotting cascade activation, fibrin clot formation, and clot dissolution via fibrinolysis. Coagulation depends on clotting factors, calcium, and the balance of procoagulant and anticoagulant mechanisms.

Normal iron metabolism involves absorption in the duodenum, transport via transferrin, and storage as ferritin/hemosiderin in the liver, spleen, and marrow. Disruption leads to iron-deficiency anemia or iron overload.

Age-related changes include reduced marrow mass, fragile RBC membranes, decreased serum iron and erythropoietin response, and impaired lymphocyte function, increasing risks of anemia, infection, and clotting problems.

Assessment involves subjective data (history of anemia, bleeding, clotting disorders, transfusions, medications like anticoagulants/chemotherapy, surgeries like gastrectomy or splenectomy, alcohol/smoking, nutrition, and family history). Functional health patterns address fatigue, bleeding, infections, diet, elimination, activity tolerance, coping, and psychosocial concerns.

Physical exam includes inspection of skin for pallor, jaundice, petechiae, ecchymoses, or lesions; palpation of lymph nodes, liver, and spleen; and assessment for musculoskeletal pain, neurologic deficits (paresthesias, ataxia), and mucosal changes (glossitis, gum bleeding). Abnormal findings such as lymphadenopathy, hepatosplenomegaly, or smooth tongue guide further investigation.

Diagnostic studies include:

CBC with differential & peripheral smear – evaluates counts, morphology, and function.

Clotting studies – PT, INR, aPTT, fibrinogen, D-dimer, platelet counts.

Iron studies – serum iron, ferritin, transferrin, TIBC, transferrin saturation.

Vitamin levels – folate, cobalamin, homocysteine, MMA.

Bone marrow aspiration/biopsy – evaluates hematopoiesis and cytogenetics.

Lymph node biopsy – diagnoses lymphoma or metastatic disease.

Molecular and cytogenetic tests – flow cytometry, PCR, FISH for leukemia/lymphoma mutations.

Imaging studies – CT, MRI, PET, bone scans for cancer or organ involvement.


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