Anemia Evaluation and Management

Anemia Basics - Red Cell Rundown

• WHO Definition: Hb levels: Men <13 g/dL; Women (non-preg) <12 g/dL; Women (preg) <11 g/dL.
• MCV Classification (RBC size):
  • Microcytic: MCV <80 fL (small)
  • Normocytic: MCV 80-100 fL (normal)
  • Macrocytic: MCV >100 fL (large)
• Key Red Cell Indices:
  • MCV: Mean Corpuscular Volume.
  • RDW: Red Cell Distribution Width (anisocytosis).
  • Reticulocyte Count: Bone marrow RBC production.

⭐ RDW is typically increased in Iron Deficiency Anemia (IDA) but normal in Thalassemia trait, aiding microcytic anemia differentiation.

Diagnostic Drilldown - Sleuthing Anemia

• Clinical Clues: Detailed history (diet, blood loss, drugs, family Hx), thorough exam (pallor, jaundice, glossitis, koilonychia, splenomegaly).
• Core Labs:
  • CBC: Hb, MCV (<80 Micro, 80-100 Normo, >100 Macro fL), MCHC, RDW.
  • Reticulocyte Count: Index marrow response. Reticulocyte Production Index (RPI) <2 indicates hypoproliferation.
  • Peripheral Smear: RBC morphology (key diagnostic clues!), WBC & platelet assessment.
• Targeted Tests (MCV/RPI-guided):
  • Iron studies (Serum Ferritin, Fe, TIBC, %Saturation).
  • Serum B12/Folate levels.
  • Hemolysis screen (LDH, Indirect Bilirubin, Haptoglobin, Coombs test).
  • Hb Electrophoresis (thalassemia, hemoglobinopathies).
  • Bone Marrow Exam (if diagnosis remains unclear).

⭐ Serum ferritin <15-30 ng/mL is the most specific non-invasive test for iron deficiency anemia (IDA).

Key Anemia Types - Common Culprits

⭐ In B12 deficiency, neurological symptoms (e.g., subacute combined degeneration) can precede or occur without macrocytic anemia.

Other Anemias & Tx - Beyond Basics

• Hemolytic Anemias:
  • Types: Intrinsic (e.g., G6PD deficiency, Sickle Cell, Thalassemia) vs. Extrinsic (e.g., AIHA, MAHA).
  • Key Tests: ↑LDH, ↑Indirect Bilirubin, ↓Haptoglobin, Reticulocytosis. Peripheral smear (schistocytes, spherocytes).
• Anemia of Chronic Disease (ACD):
  • Pathophysiology: ↑Hepcidin → ↓Iron absorption & release from stores.
  • Labs: ↓Serum Fe, ↓/Normal TIBC, ↑/Normal Ferritin.
• Aplastic Anemia:
  • Hallmark: Pancytopenia with a hypocellular bone marrow.
  • Key: Often no hepatosplenomegaly or lymphadenopathy.
• General Management & Transfusion:
  • Treat the underlying cause first.
  • Transfusion Triggers:

⭐ In Aplastic Anemia, the absence of hepatosplenomegaly and lymphadenopathy is a crucial finding, helping differentiate it from hematological malignancies that can also present with pancytopenia.

High‑Yield Points - ⚡ Biggest Takeaways

• Initial anemia workup: CBC, reticulocyte count, peripheral smear.
• MCV classifies anemia: Microcytic (IDA, thalassemia), Normocytic (ACD), Macrocytic (megaloblastic).
• Iron Deficiency Anemia: ↓Ferritin, ↑TIBC; koilonychia, pencil cells.
• Megaloblastic Anemia: B12/Folate deficiency; hypersegmented neutrophils; neuropathy in B12 deficiency.
• Anemia of Chronic Disease: ↑Ferritin (or normal), ↓serum iron, ↓TIBC.
• Hemolytic Anemias: Reticulocytosis, ↑LDH, ↑indirect bilirubin; specific red cell morphology.
• Beta-Thalassemia Minor: Microcytic with ↑HbA2 (>3.5%) and target cells.