Normocytic

Normocytic Anemias

Characteristics: Normal-sized RBCs (MCV 80-100 fL)
Key Considerations:
- Evaluate reticulocyte count to determine if the bone marrow is responding appropriately to the anemia
  - High Reticulocyte Count: Suggests increased RBC destruction (hemolysis) or acute blood loss
  - Low Reticulocyte Count: Suggests decreased RBC production due to bone marrow disorders, chronic diseases, or early nutritional deficiencies
Common Causes:
- Acute Blood Loss:
  - Sudden loss of blood due to trauma, surgery, or gastrointestinal bleeding
  - Initial CBC may be normocytic and normochromic, but iron deficiency can develop over time
- Hemolytic Anemias:
  - Increased destruction of RBCs due to inherited or acquired causes
  - Peripheral blood smear: May show spherocytes, schistocytes, or other abnormal RBC morphologies
  - Lab findings:
    - Elevated reticulocyte count
    - Elevated indirect bilirubin
    - Elevated lactate dehydrogenase (LDH)
    - Decreased haptoglobin
    - Positive direct antiglobulin test (DAT) in autoimmune hemolytic anemia
  - Inherited Hemolytic Anemias:
    - Hereditary spherocytosis: Membrane defect leading to spherical RBCs
    - Sickle cell anemia: Abnormal hemoglobin (HbS) leading to sickling of RBCs
    - Thalassemia: (Can also cause microcytic anemia.)
    - G6PD deficiency: Enzyme deficiency leading to oxidative damage
  - Acquired Hemolytic Anemias:
    - Autoimmune hemolytic anemia: Antibodies against RBCs
    - Drug-induced hemolytic anemia: Caused by certain medications
    - Microangiopathic hemolytic anemia (MAHA): Mechanical destruction of RBCs in small blood vessels (e.g., thrombotic thrombocytopenic purpura (TTP), hemolytic uremic syndrome (HUS), disseminated intravascular coagulation (DIC))
- Anemia of Chronic Disease/Inflammation:
  - (Can also cause microcytic anemia.)
- Aplastic Anemia:
  - Bone marrow failure resulting in decreased production of all blood cell lines (pancytopenia)
  - Causes: Autoimmune, drug-induced, infections, or inherited
  - Bone marrow examination: Hypocellular marrow
- Chronic Kidney Disease:
  - Decreased production of erythropoietin (EPO)
  - Peripheral blood smear: Normocytic, normochromic RBCs

Laboratory Tests for Anemia

Complete Blood Count (CBC):
- Hemoglobin (HGB)
- Hematocrit (HCT)
- Red Blood Cell Count (RBC)
- Mean Corpuscular Volume (MCV)
- Mean Corpuscular Hemoglobin (MCH)
- Mean Corpuscular Hemoglobin Concentration (MCHC)
- Red Cell Distribution Width (RDW)
- White Blood Cell Count (WBC) and Differential
- Platelet Count
Peripheral Blood Smear:
- RBC morphology (size, shape, color)
- WBC differential
- Platelet estimate
Reticulocyte Count:
- Percentage and absolute number of reticulocytes
- Corrected Reticulocyte Count/Reticulocyte Production Index (RPI)
Iron Studies:
- Serum Iron
- Total Iron-Binding Capacity (TIBC)
- Transferrin Saturation
- Ferritin
Vitamin B12 and Folate Levels:
- Serum B12
- Red Blood Cell Folate
Methylmalonic Acid (MMA) and Homocysteine Levels:
- Elevated in B12 Deficiency
- Homocysteine also Elevated in Folate Deficiency
Hemoglobin Electrophoresis:
- Identifies abnormal hemoglobin variants (e.g., HbS, HbC)
Direct Antiglobulin Test (DAT):
- Detects antibodies or complement proteins on the surface of RBCs
Bone Marrow Examination:
- Cellularity
- Maturation of cell lines
- Presence of abnormal cells
Other Tests:
- Haptoglobin and LDH (for hemolysis)
- Coombs test (for autoimmune hemolytic anemia)
- Osmotic Fragility Test (for hereditary spherocytosis)
- G6PD Assay (for G6PD deficiency)

Key Terms

Anemia: Deficiency of red blood cells or hemoglobin
Normocytic: Normal-sized red blood cells (MCV 80-100 fL)
Hyperchromic: Increased hemoglobin content (intensely colored)
Reticulocyte: Immature red blood cell
Hemolysis: Destruction of red blood cells
Extramedullary Hematopoiesis: Blood cell production outside the bone marrow
Pancytopenia: Deficiency of all blood cell lines (RBCs, WBCs, platelets)

Porphyria

Hereditary Hemolytic