Makindo Medical Notes

Related Subjects: |Iron deficiency Anaemia |Haemolytic anaemia |Macrocytic anaemia |Megaloblastic anaemia |Microcytic anaemia |Myelodysplasia |Myelofibrosis

⚠️ Teaching Pearl: Once daily or alternate-day ferrous sulphate (FeSO₄) is sufficient. Please stop prescribing TDS iron — it only increases side effects without improving absorption.

📖 About

• Reduced Hb for age/sex.
• Microcytosis: red cells < 80 fl (low MCV).
• Often detected incidentally on FBC; must be explained and not dismissed.

🧬 Aetiology / Pathophysiology

• Red cell production is driven by Erythropoietin.
• If haemoglobin cannot be produced adequately, precursors undergo more divisions → smaller red cells.
• Microcytosis reflects the “limiting factor” in haem synthesis:
  • Iron deficiency → lack of iron.
  • Thalassaemia → globin chain synthesis failure.
  • Chronic disease → impaired iron mobilisation.
  • Sideroblastic → impaired incorporation of iron into haem.

⚠️ Causes of Microcytic Anaemia

• Iron Deficiency Anaemia (IDA): ↓ ferritin, ↓ serum iron, ↑ TIBC, ↓ transferrin saturation. [No iron in bone marrow]
• Thalassaemia trait: Very low MCV, normal/high ferritin, ↑ HbA2 on electrophoresis.
• Anaemia of Chronic Disease: Normal/↑ ferritin, ↓ serum iron, ↓ TIBC (iron sequestered in macrophages).
• Sideroblastic anaemia: Hypochromic cells, ↑ iron in marrow, ring sideroblasts on staining.
• Toxicity: Lead or aluminium poisoning.

🩺 Clinical Features

• General: Fatigue, weakness, exertional dyspnoea.
• Skin/nails: Koilonychia (spoon nails), brittle nails, pallor.
• Mucosa: Glossitis, angular cheilitis.
• Cardiac: Flow murmurs in severe anaemia.
• Clues to cause: Menstrual loss, NSAID/aspirin use, GI symptoms, ethnicity (thalassaemia risk).

🔎 Investigations

• FBC: Microcytosis, hypochromia, anisopoikilocytosis.
• Iron studies:
  • IDA → ↓ ferritin, ↓ serum iron, ↑ TIBC, ↓ transferrin saturation.
  • ACD → ↑ ferritin, ↓ serum iron, ↓ TIBC.
• Raised soluble transferrin receptors (newer marker for IDA).
• Blood film: Hypochromic microcytes.
• Bone marrow: Erythroid hyperplasia ± absent iron stores.
• Identify bleeding source: OGD, colonoscopy, small bowel studies, technetium-labelled RBC scan.
• Other: Pelvic USS for gynae blood loss, Hb electrophoresis for thalassaemia.

🌍 Causes of Iron Deficiency Anaemia

• Blood loss: GI tract (ulcer, cancer, angiodysplasia), urinary tract, epistaxis, hookworm (worldwide commonest).
• Physiological: Pregnancy, growth spurts.
• Increased demand: Adolescence, chronic illness.
• Malabsorption: Coeliac disease, post-gastrectomy.
• Poor intake: Malnutrition, restrictive diets.

💊 Management

• Always identify and investigate cause → especially upper and lower GI endoscopy in older patients (GI cancer until proven otherwise).
• Iron replacement: Ferrous sulphate 200 mg OD or alternate days × 3–6 months. Monitor Hb rise (1 g/dL per week expected).
• IV iron if intolerant to oral or need rapid replenishment.
• Other: Chelation therapy if lead toxicity, pyridoxine may help sideroblastic anaemia.
• Transfusion only if severe/symptomatic or ongoing blood loss.

Cases — Microcytic Anaemia (5 Examples)

• Case 1 — Iron Deficiency Anaemia (IDA): A 42-year-old woman presents with fatigue, pica, and brittle nails. She has heavy menstrual bleeding. Hb 8.9 g/dL, MCV 68 fL, ferritin 7 µg/L. Blood film shows hypochromic microcytes. Diagnosis: IDA secondary to menorrhagia.
• Case 2 — β-Thalassaemia Trait: A 25-year-old man of Mediterranean origin is found to have microcytosis on routine testing (Hb 12 g/dL, MCV 62 fL). Ferritin is normal. Hb electrophoresis shows HbA₂ 5.5%. Blood film: target cells. Diagnosis: β-thalassaemia minor (carrier state).
• Case 3 — Anaemia of Chronic Disease (ACD): A 70-year-old man with long-standing rheumatoid arthritis develops mild anaemia. Hb 10.5 g/dL, MCV 78 fL. Iron low, ferritin high, TIBC low. Blood film: normochromic–microcytic picture. Diagnosis: ACD due to chronic inflammation.
• Case 4 — Sideroblastic Anaemia (Alcohol-Related): A 60-year-old man with heavy alcohol use presents with pallor and fatigue. Hb 9.2 g/dL, MCV 72 fL. Iron and ferritin raised. Bone marrow aspirate: ring sideroblasts. Diagnosis: Acquired sideroblastic anaemia from alcohol toxicity.
• Case 5 — Lead Poisoning: A 12-year-old boy living in an old house presents with abdominal pain, learning difficulties, and anaemia. Hb 8.0 g/dL, MCV 74 fL. Blood film: basophilic stippling. Serum lead level high. Diagnosis: Microcytic anaemia due to lead poisoning.

Teaching Commentary 🧾

These cases illustrate the five classic causes of microcytosis: - IDA: Low ferritin, high TIBC, hypochromic film. - Thalassaemia: Marked microcytosis, normal iron, raised HbA₂, target cells. - ACD: Low iron, low TIBC, normal/high ferritin. - Sideroblastic: High iron, abnormal ring sideroblasts, often alcohol/drug related. - Lead poisoning: Basophilic stippling, neurological/GI symptoms. In exams, pattern recognition (iron studies + blood film) is crucial to distinguishing between them.