Hematology

Introduction

  • Objective: Simplify the concepts of hematology and oncology.

  • Importance: Hematology and oncology make up 12% of board exams; growing relevance with over 15 million cancer survivors in the US.

Overview of Hematology Topics

  • Division of topics:

    • Red cell disorders (primarily anemias, hemochromatosis)

    • Disorders of hemostasis (bleeding, clotting)

    • Bone marrow disorders and hematologic cancers (myeloproliferative neoplasms, lymphomas, leukemias, plasma cell disorders).

Red Cell Disorders

Anemias

  • Iron Deficiency Anemia:

    • Most common cause of anemia.

    • Symptoms: fatigue, weakness, pale appearance.

    • Signs: microcytic (small) and hypochromic (pale) red blood cells, low reticulocyte count.

    • Key Diagnostic: Low serum ferritin (<40).

    • Treatment: Oral or IV iron.

Unique Symptoms of Iron Deficiency

  • Cravings for ice or dirt (pica), restless leg syndrome.

  • Recognize CBC patterns to distinguish from leukemia.

Anemia of Inflammation (formerly Anemia of Chronic Disease)

  • Impaired utilization of iron, often normal or elevated ferritin levels.

  • Differentiate from iron deficiency anemia with TIBC and reticulocyte counts.

Other Anemias

  • Megaloblastic Anemia: Due to B12 or folate deficiency.

    • Causes: pernicious anemia, malabsorption, dietary causes.

    • Associated signs: neurological symptoms in B12 deficiency; macrocytic red blood cells and hypersegmented neutrophils on blood smear.

    • Diagnostic confirmation via B12 serum levels and metabolites (methylmalonic acid).

Hemolytic Anemias

Classification

  • Intrinsic: Genetic defects (e.g., G6PD deficiency, hemoglobinopathies).

  • Extrinsic: Acquired issues (e.g., autoimmune hemolytic anemia).

Clinical Clues

  • Look for jaundice, dark urine, elevated indirect bilirubin, low haptoglobin.

  • Schistocytes on blood smear indicates hemolysis.

Sickle Cell Disease and Thalassemias

  • Symptoms of sickle cell: pain crises, risk of infection, splenic infarcts.

  • Thalassemias often misdiagnosed as iron deficiency anemia due to microcytic nature; ruled out with hemoglobin electrophoresis.

Bone Marrow Disorders and Hematologic Cancers

  • Aplastic Anemia: Pancytopenia with hypocellular bone marrow; treatment includes transplants or immunosuppression.

  • Myelodysplastic Syndromes: Hypercellular marrow; risk of progression to leukemia.

  • Leukemias: Differentiated as AML or ALL based on maturity of cells and associated features (e.g., CNS involvement in ALL).

Disorders of Hemostasis

Primary Hemostasis Problems

  • Primary hemostatic defects lead to superficial bleeding (e.g., ITP, TTP).

  • Work-up includes PT, PTT, platelet count.

Secondary Hemostasis Problems

  • Severe bleeding symptoms; diagnostic mixing studies used to determine whether deficiencies or inhibitors are present.

  • Common issues: hemophilia, vitamin K deficiency.

Specific Disorders

  • ITP: IgG mediated, often found in young adults, excessive bruising.

  • TTP: Characterized by schistocytes on smear, requires immediate plasma exchange.

  • DIC: Often associated with OB complications, cancer, presenting with bleeding and abnormal coags.

Conclusion of Hematology Section

  • Recap of the major red cell disorders, anemias, and disorders of hemostasis, emphasizing adherence to diagnostics and management strategies for better patient outcomes.

Oncology Overview

Common Hematologic Cancers

  • Acute Lymphoblastic Leukemia (ALL): Lymphadenopathy, hepatosplenomegaly; higher risk in pediatrics.

  • Chronic Lymphocytic Leukemia (CLL): Older patients with lymphocytosis, smudge cells on smear.

  • Acute Myeloid Leukemia (AML): Presence of Auer rods; treat acutely with emergency protocols in case of hyperleukocytosis.

Myeloma and Plasma Cell Disorders

  • Symptoms: Hypercalcemia, renal insufficiency (CRABS), requires SPEP/UPEP for diagnosis.

  • Monoclonal gammopathy monitored; treatment includes bortezomib, lenalidomide.

Final Thoughts

  • Emphasis on integrating knowledge of blood disorders informs clinical diagnosis and management.

  • Recognize patterns and symptoms that inform practical applications in both exams and clinical practice.