IM9.1-2 | Anaemia Foundations — Summary & Reflection

KEY TAKEAWAYS

Anaemia is defined by WHO thresholds (Hb <13.0 g/dL in adult males, <12.0 g/dL in non-pregnant women, <11.0 g/dL in pregnant women). Severity is mild/moderate/severe/life-threatening based on Hb level; onset rate matters as much as level.

Morphological classification by MCV:
- Microcytic (MCV <80 fL): IDA (high RDW, low ferritin, high TIBC), thalassaemia (normal RDW, normal ferritin, elevated HbA2), ACD (~25–30% cases), sideroblastic
- Normocytic (MCV 80–100 fL): ACD (70–75%), haemolytic anaemia, acute blood loss, aplastic anaemia, renal failure, mixed deficiency (dimorphic film)
- Macrocytic (MCV >100 fL): megaloblastic (B12/folate — macro-ovalocytes + hypersegmented neutrophils), non-megaloblastic (liver disease, hypothyroidism, alcohol, drugs)

Kinetic classification by reticulocyte index:
- Hyperproliferative (RI >2.5): haemolysis or acute blood loss
- Hypoproliferative (RI <2.0): nutritional deficiency, ACD, renal failure, aplasia

India-specific prevalence: IDA (most common — 57% of reproductive-age women), β-thalassaemia trait (~3.4% carrier rate, 10–15 K major births/year), SCD (tribal central India), G6PD deficiency (7–8% of males), dietary B12 deficiency (vegetarian population)

Key discriminating tests: serum ferritin (IDA vs ACD); MMA (B12 vs folate); HPLC (haemoglobinopathies); DAT (AIHA); peripheral blood film morphology (shapes tell the diagnosis)

REFLECT

Return to the three patients from the opening hook — Rekha (pica, smooth tongue, microcytic hypochromic cells — IDA with dietary cause and likely hookworm), Suresh (melaena, microcytic — IDA from GI bleeding requiring GI malignancy exclusion), and Vijay (macrocytic, sensory ataxia — B12 deficiency with subacute combined degeneration). All three have anaemia, but the morphological signatures on the blood film and the supportive biochemistry led you down entirely different diagnostic and management paths. Think about your next patient in the anaemia OPD: what three findings on the blood film would tell you the diagnosis before you even order a biochemical test? And how would you explain to a mother whose child has been empirically given iron supplements for 3 months without improvement that thalassaemia trait — not iron deficiency — is the real cause? Connecting morphological pattern recognition to efficient investigation and clear communication is the core clinical skill this foundation module builds.