Hemolytic Anemia Overview

Hemolytic Anemia

• G6PD deficiency causes hemolytic anemia due to oxidative stress, leading to hemoglobin oxidation and precipitation of hemichrome.
• Hemoglobin oxidation forms precipitates called Heinz bodies.
• G6PD deficiency is an X-linked recessive disorder, more common in males.

Anemia of Chronic Disease

• Anemia of chronic disease is characterized by mild to moderate anemia that progresses from normocytic to microcytic when advanced.
• Iron metabolism is altered, and hepcidin regulates the entry of iron into circulation in anemia of chronic disease.

Autoimmune Hemolytic Anemia

• Fava beans, infection, and certain drugs can trigger autoimmune hemolytic anemia.
• The underlying cause of autoimmune hemolytic anemias is intrinsic/hereditary, related to immune system abnormality.
• The most common cause of hemolytic anemia in sickle cell disease is autoimmune hemolytic anemia.

Hemolytic Anemia Mechanisms

• Oxidative stress leading to hemoglobin oxidation and precipitation of hemichrome is the cause of hemolytic anemia in G6PD deficiency.
• Immune-mediated destruction of RBCs occurs in autoimmune hemolytic anemia.
• Destruction of RBCs in drug-induced extrinsic hemolytic anemia is caused by immune complex-mediated mechanisms.

Immune Response

• Macrophages are the predominant phagocyte in the late inflammatory response.
• Cytokines and chemokines regulate innate or adaptive resistance by affecting other neighboring cells.
• Interferons play a primary role in the immune response, inducing an antiviral state in cells.
• Neutrophils are the most numerous leukocyte type.

Eosinophils and Wound Repair

• Eosinophils play a role in the immune response, particularly in parasitic infections and allergic reactions.
• Fibroblasts are produced in the bone marrow and involved in wound repair.

Tumor Necrosis Factor

• Tumor necrosis factor plays a role in the immune response, inducing apoptosis in infected cells.
• Granulocytes contain lysosomes that enable them to destroy microorganisms.
• Chemokines play a key role in the immune response, attracting immune cells to the site of inflammation.

Systemic Lupus Erythematosus

• Systemic lupus erythematosus is a type III hypersensitivity reaction, associated with the formation of immune complexes.
• B cells produce autoantibodies in systemic lupus erythematosus.
• The condition predominantly affects females, with a higher prevalence in African Americans.
• The kidneys are the most commonly affected organ by kidney damage in systemic lupus erythematosus.
• Immune complexes deposited in systemic lupus erythematosus consist primarily of DNA and histone proteins.
• Four or more findings indicative of systemic lupus erythematosus are required for diagnosis.

Platelets and Hemostasis

• Platelets play a primary role in hemostasis, forming a platelet plug at the site of vascular injury.
• Thromboxane A2 is required for the activation of clotting factors in the clotting cascade.
• Platelets have a lifespan of 7-10 days in the bloodstream.
• Glycoproteins on the surface of platelets enable platelet activation and aggregation.
• Sudden pooling of blood, hypovolemia, and circulatory collapse characterize disseminated intravascular coagulation (DIC).
• Thromboxane A2 induces platelet contraction and clot retention at the site of vascular injury.

Clotting Cascade

• Tissue injury outside the vessel activates the extrinsic pathway of the clotting cascade.
• Thrombin plays a primary role in the clotting process, converting fibrinogen to fibrin.
• Prothrombin activator is induced by tissue factor in the clotting cascade.
• Injury to the vessel induces the formation of prothrombin activator, allowing the clotting cascade to proceed.

Leukemias

• Acute lymphoblastic leukemia (ALL) is most responsive to therapy.
• Chronic lymphocytic leukemia (CLL) often presents with constitutional symptoms, recurrent infections, and easy bruising/bleeding.
• Chronic myeloid leukemia (CML) involves neoplastic clonal proliferation of myeloid stem cells and has a chronic course for years until transforming to acute leukemia.
• Hairy cell leukemia is characterized by anemia, neutropenia, recurrent infections, and splenomegaly.
• Acute myeloid leukemia (AML) often presents with fatigue, weight loss, pallor, rashes, and bone tenderness and pain in the advanced stages.
• Chronic lymphocytic leukemia (CLL) is least aggressive and is commonly discovered on routine CBC due to generalized painless lymphadenopathy and splenomegaly.
• Acute promyelocytic leukemia (APL) involves Philadelphia syndrome, where patients have shorter survival and do not respond to therapy.

Test your knowledge about hemolytic anemia, including its causes, types, and symptoms. Learn about intrinsic and extrinsic factors contributing to this condition, as well as specific examples such as autoimmune hemolytic anemias and drug-induced hemolysis.