Types of Anemia Lecture Notes

Introduction

• Definition of Anemia:
  • Low oxygen carrying capacity
  • Low amount of red blood cells or dysfunctional red blood cells
• Indicator: Seen on hematocrit; low PCV or HCV (< 45%)

Types of Anemia

Iron Deficiency Anemia

• Symptoms:
  • Shortness of breath (SOB or dyspnea)
  • Fatigue
  • Increased workload on the heart leading to tachycardia
  • Dizziness or syncope
• Mechanism:
  • Iron is crucial for hemoglobin (Hgb) synthesis (heme production)
  • Low iron → Low heme → Low Hgb → Smaller and less functional RBCs
  • Measured by MCV (Mean Corpuscular Volume): MCV < 90 fL (microcytic anemia)
• Causes:
  • Blood loss (e.g., ulcers)
  • Heavy menstruation (menorrhagia)
  • Low iron diet (common in vegetarians)
• Treatment:
  • Iron supplements
  • Possibly transfusions

Pernicious Anemia (B-12/Folic Acid Deficiency)

• Importance of B-12/Folic Acid:
  • Necessary for DNA synthesis and maturation of RBCs
• Mechanism:
  • Absorbed B-12 binds to intrinsic factor in the stomach
  • Autoimmune condition: antibodies attack intrinsic factor, preventing B-12 absorption
  • Results in large, immature RBCs (macrocytic anemia; MCV > 90 fL)
• Symptoms: Same as general anemia symptoms
• Treatment:
  • Intramuscular B-12 injections

Hereditary Spherocytosis

• Cause: Genetic mutation in membrane proteins (spectrin, ankyrin)
• Effect: RBCs become spherical and are hemolyzed in the spleen
• Symptoms: General anemia symptoms + splenomegaly
• Diagnosis: Coombs test

G6PDH (Glucose-6-Phosphate Dehydrogenase) Deficiency

• Importance of G6PDH:
  • Supports antioxidant defenses via NADPH production
  • Reduces glutathione to combat reactive oxygen species (ROS)
• Effect: Lack of G6PDH → ROS damage → Hemoglobin precipitation (Heinz bodies) → Hemolytic anemia
• Symptoms: General anemia symptoms + presence of Heinz bodies in RBCs

Sickle Cell Anemia

• Cause: Missense mutation (glutamic acid → valine at 6th position of beta chain)
• Mechanism: Deoxygenated hemoglobin polymerizes, distorting RBC into sickle shape
• Symptoms:
  • Vaso-occlusive crises (e.g., priapism, splenomegaly)
  • General anemia symptoms
• Treatment:
  • Oxygen therapy, pain relievers, fluids
  • Hydroxyurea to increase fetal hemoglobin
  • Regular transfusions
• Additional Note: Provides resistance to malaria

Hemorrhagic Anemia

• Cause: Blood loss (acute or chronic)
• Mechanism: Decreased RBCs → Decreased oxygen carrying capacity
• Examples: Trauma, ulcers, aneurysms
• Treatment: Treat source of bleeding, transfusions

Aplastic Anemia

• Cause: Bone marrow damage (drugs, viruses, radiation, etc.)
• Effect: Pancytopenia (reduced RBCs, WBCs, platelets)
• Symptoms:
  • General anemia symptoms
  • Increased infections (low WBCs)
  • Increased bruising/bleeding (low platelets, petechiae)
• Treatment: Bone marrow transplant

Thalassemia

• Common in: Mediterranean ancestry
• Cause: Genetic defect in hemoglobin chains (alpha/beta)
• Effect: Faulty or missing globin chain → Small RBCs (microcytic anemia)
• Treatment:
  • Regular transfusions
  • Bone stem cell transplant (ideal)
  • Iron supplements and oxygen

Summary of Anemias

• Microcytic anemias: Iron deficiency, Thalassemia
• Macrocytic anemia: B-12/Folic acid deficiency
• Hemolytic anemias: Hereditary spherocytosis, G6PDH deficiency, Sickle cell anemia
• Aplastic anemia: Associated with pancytopenia
• Hemorrhagic anemia: Due to blood loss

Treatments Overview

• Iron deficiency: Iron supplements
• B-12 deficiency: Intramuscular injections
• Hereditary conditions: Address underlying mutations, manage symptoms
• Hemorrhagic anemia: Treat cause of bleeding and provide transfusions
• Aplastic anemia: Bone marrow transplant, symptomatic treatment
• Thalassemia: Transfusions, possibly bone stem cell transplant