Classification of Anaemias

•    Microcytic: MCV < 80 fL → TICS: Thalassaemia, Iron deficiency, Chronic disease (rare), Sideroblastic

•    Normocytic: MCV 80–100 fL → ABCD: Acute blood loss, Bone marrow failure, Chronic disease,

    Destruction (haemolysis)

•    Macrocytic: MCV > 100 fL → B12/folate deficiency, liver disease, alcohol, reticulocytosis, hypothyroidism, 

    drugs (hydroxyurea, AZT)

 Red Cell Indices and Morphology

•    MCV: Mean corpuscular volume → classifies anaemia

•    MCH: Mean corpuscular Hb → low in iron deficiency

•    RDW: ↑ in iron deficiency, variable cell size

•    Morphology clues:

o    Target cells → liver disease, thalassaemia

o    Teardrop cells → myelofibrosis

o    Schistocytes → MAHA

o    Spherocytes → AIHA or hereditary spherocytosis

 Microcytic Anaemia – Causes

•    Iron deficiency – most common worldwide

•    Thalassaemia – microcytic, hypochromic, normal iron

•    Sideroblastic anaemia – ring sideroblasts in marrow

•    Chronic disease – occasionally microcytic

 Macrocytic Anaemia – Causes

•    Megaloblastic: B12 or folate deficiency

•    Non-megaloblastic: Alcohol, liver disease, hypothyroidism

•    Drugs: Methotrexate, hydroxyurea, phenytoin, zidovudine

•    Reticulocytosis: falsely raises MCV due to large retics

 Normocytic Anaemias

•    Acute blood loss

•    Anaemia of chronic disease

•    Renal disease – ↓ erythropoietin

•    Haemolysis – may be normocytic

•    Bone marrow failure – aplastic anaemia, myelodysplasia

 Iron Deficiency Anaemia

•    Low ferritin, high TIBC, low serum iron

•    Causes: blood loss (e.g. GI, menstruation), poor intake, malabsorption (e.g. coeliac)

•    Features: koilonychia, angular stomatitis, pica

•    Rx: oral iron (ferrous sulfate), IV iron if intolerant/malabsorption

 Thalassaemias

•    α-thalassaemia: gene deletion, SE Asia; HbH, hydrops fetalis

•    β-thalassaemia: point mutation, Mediterranean; target cells

•    Trait vs major: major needs transfusion + chelation

•    Normal iron studies, unlike iron deficiency

 Sideroblastic Anaemia

•    Defective haem synthesis → ring sideroblasts (Prussian blue)

•    Causes: congenital, alcohol, lead, isoniazid, myelodysplasia

•    Iron overload with microcytic anaemia

•    High ferritin, ↑ transferrin saturation

 Anaemia of Chronic Disease

•    ↓ serum iron, ↓ TIBC, normal/high ferritin

•    Due to inflammatory cytokines → hepcidin inhibits iron release

•    Associated with RA, CKD, infections, malignancy

•    Treat underlying cause; consider EPO in CKD

 Megaloblastic Anaemia (B12/Folate Deficiency)

•    B12 deficiency: vegan diet, pernicious anaemia, ileal disease

•    Folate deficiency: alcoholism, poor diet, pregnancy, drugs (MTX)

•    Features: glossitis, neuro signs (B12 only), pancytopenia

•    Rx: IM B12; never give folate before B12!

 Aplastic Anaemia

•    Pancytopenia with hypocellular marrow

•    Causes: idiopathic, drugs (chloramphenicol, chemo), radiation, viruses (EBV, parvovirus B19)

•    Rx: supportive care, bone marrow transplant, immunosuppression

 Anaemia in Renal Disease

•    Normocytic anaemia due to ↓ erythropoietin

•    May be exacerbated by chronic inflammation, reduced RBC survival

•    Rx: EPO-stimulating agents + iron supplementation

 Approach to Anaemia in Clinical Practice

•    Step 1: Confirm anaemia (Hb low for age/sex)

•    Step 2: Check MCV → classify as micro/normo/macrocytic

•    Step 3: Look at reticulocyte count – low in marrow failure, high in haemolysis/bleeding

•    Step 4: Assess iron status, B12/folate, renal function, CRP

•    Step 5: Blood film and further tests guided by initial findings