PA13.2-4 | Approach to Anemia: Classification & Diagnostic Workup — Summary & Reflection

REFLECT

Before you move on, take 3 minutes to do this:

1. Draw the 5-step anemia workup flowchart from memory on a blank sheet. Start with 'CBC shows low Hb' and trace all three MCV branches to at least two causes each.

1. Think of one patient you have seen (or read about) during your clinical postings with pallor or fatigue. Which step of the algorithm would have been the decisive branch point for their diagnosis?

1. Reflect: in what clinical scenario would you bypass the full workup and act immediately on Hb alone — without waiting for MCV, retic count, or smear? Write down the Hb threshold and the action you would take.

These three exercises consolidate the decision-tree into procedural memory — the kind of memory that fires automatically at 3 AM in a casualty. The next SDL (Lab Skills: Hb Estimation & Manual Counts) will take you into the laboratory to generate the numbers you have been interpreting today.

KEY TAKEAWAYS

Core take-aways from this SDL:

1. Anemia is a sign, not a diagnosis — always identify the underlying cause using the systematic 5-step framework.

1. MCV is the first branch point: microcytic (< 80 fL) → hemoglobin synthesis problem; normocytic (80–100) → diverse causes including mixed deficiency; macrocytic (> 100) → impaired DNA synthesis or reticulocytosis.

1. Reticulocyte Production Index (RPI) distinguishes hypoproliferative (RPI < 2, production failure) from hyperproliferative (RPI > 2, hemolysis or blood loss) — it is the marrow's report card.

1. WHO severity grading: mild (Hb 10–12 g/dL women), moderate (8–10), severe (< 8), life-threatening (< 6.5) — but clinical adaptation matters.

1. The peripheral smear is mandatory — it catches diagnoses that MCV and retic count miss (schistocytes, blasts, sickle cells, dimorphic picture).

1. Indian context: hookworm is the leading cause of IDA in rural adult males; nutritional IDA dominates in women of reproductive age; mixed deficiencies are common in vegetarian populations and can produce a falsely normal MCV.

1. The 5-step algorithm: Confirm + grade → MCV branch → Retic/RPI → Peripheral smear → Targeted investigations.

The downstream SDLs (Microcytic, Macrocytic, Hemolytic, Aplastic) will each pick up from the appropriate branch of this decision tree. Carry this framework forward.