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Haemolytic anemia from davidson

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Davidson's Principles and Practice of Medicine haemolytic anaemia diagnosis classification

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Haemolytic anaemia

Definition: Anaemia caused by premature destruction of red blood cells, reducing their normal survival of about 120 days. Bone marrow compensates by increasing erythropoiesis, producing reticulocytosis.

Classification

TypeCauses
Inherited (intrinsic RBC defects)Hereditary spherocytosis, G6PD deficiency, pyruvate kinase deficiency, sickle-cell disease, thalassaemia
Acquired immuneWarm autoimmune haemolytic anaemia, cold agglutinin disease, drug-induced immune haemolysis, alloimmune reaction such as mismatched transfusion or haemolytic disease of the newborn
Acquired non-immuneMicroangiopathic haemolytic anaemia (TTP, HUS, DIC, malignant hypertension), mechanical valves, severe burns, infections such as malaria, toxins, PNH, hypersplenism

Site of haemolysis

  • Extravascular haemolysis: RBCs are removed by macrophages in the spleen and liver. Seen in hereditary spherocytosis and warm autoimmune haemolytic anaemia. It causes jaundice, splenomegaly, and spherocytes.
  • Intravascular haemolysis: RBCs break down within vessels. Seen in transfusion reactions, PNH, microangiopathic haemolysis, mechanical destruction, severe G6PD-related oxidative haemolysis. It causes haemoglobinaemia, haemoglobinuria, and markedly reduced haptoglobin.

Clinical features

  • Pallor, fatigue, dyspnoea, tachycardia
  • Mild jaundice due to raised unconjugated bilirubin
  • Dark urine in intravascular haemolysis
  • Splenomegaly, especially in extravascular haemolysis
  • Pigment gallstones in chronic disease
  • Features of the cause: vaso-occlusive pain in sickle-cell disease, infection/drug exposure in G6PD deficiency, thrombosis or renal/neurological features in MAHA

Laboratory findings

Evidence of haemolysis
  • Low Hb
  • Reticulocytosis
  • Increased unconjugated bilirubin
  • Increased LDH
  • Decreased serum haptoglobin
  • Increased urinary urobilinogen
Peripheral blood film
  • Spherocytes: hereditary spherocytosis, warm AIHA
  • Schistocytes or fragmented cells: DIC, TTP, HUS, prosthetic valve haemolysis
  • Bite cells/Heinz-body-associated changes: G6PD deficiency
  • Sickle cells: sickle-cell disease
  • Agglutination: cold agglutinin disease
Direct antiglobulin test (DAT, direct Coombs test)
  • Positive in immune haemolytic anaemia.
  • The textbook library describes haemolysis as shortened red-cell survival with reticulocytosis and unconjugated hyperbilirubinaemia; antibody-coated RBCs give a positive DAT. Scott-Brown's Otorhinolaryngology Head & Neck Surgery, Vol. 1, lines 2484-2488.

Diagnostic approach

  1. Confirm haemolysis: reticulocyte count, bilirubin, LDH, haptoglobin.
  2. Examine blood film.
  3. Perform DAT to distinguish immune from non-immune haemolysis.
  4. Review drugs, transfusions, infections, family history, ethnicity, and prosthetic valves.
  5. Targeted tests may include G6PD assay, Hb electrophoresis, osmotic fragility/EMA-binding test for hereditary spherocytosis, PNH flow cytometry, coagulation screen, renal function, and malaria testing.

Principles of treatment

  • Treat the underlying cause and support the patient.
  • Give folic acid in chronic haemolysis.
  • Transfuse compatible red cells if severe or symptomatic anaemia, with urgent specialist input in autoimmune haemolysis.
  • Warm AIHA: corticosteroids first-line; rituximab or splenectomy may be considered for refractory disease.
  • Cold agglutinin disease: avoid cold exposure; treat the underlying trigger or lymphoproliferative disorder.
  • G6PD deficiency: stop oxidant drugs and treat infection.
  • Hereditary spherocytosis: folate; splenectomy for selected moderate-to-severe cases, with vaccination and infection-risk precautions.
  • MAHA/TTP: emergency specialist treatment. Suspected TTP needs urgent plasma exchange and immunosuppression.
I could not locate Davidson’s Principles and Practice of Medicine in the available textbook library, so this is a concise standard medical-textbook summary rather than a verbatim Davidson extract.
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