Lecture 5: Haemolytic Anaemias

Question 1

Define haemolytic anaemia.

Answer 1

Premature RBC destruction (<120 days), leading to anaemia. Classified as intravascular (lysis in circulation) or extravascular (macrophage-mediated in spleen/liver).

Question 2

Two main categories of causes?

Answer 2

Hereditary (e.g., membrane defects, enzyme deficiencies) and acquired (e.g., autoantibodies, infections).

Question 3

What membrane protein defect causes HS?

Answer 3

Deficiencies in ankyrin, band 3, or spectrin → loss of membrane → spherocytes.

Question 4

Key lab findings in HS?

Answer 4

FBC: ↓Hb, ↑MCHC, ↑reticulocytes.

Blood film: Spherocytes (no central pallor).

DAT: Negative (rules out immune cause).

Question 5

Why is splenectomy effective in HS?

Answer 5

Removes site of extravascular haemolysis (but ↑infection risk post-op).

Question 6

Difference between warm and cold AIHA?

Answer 6

Warm AIHA (80%): IgG antibodies (37°C); spherocytes on film.

Cold AIHA (10%): IgM antibodies (<4°C); cold agglutinins.

Question 7

What does a positive DAT indicate?

Answer 7

Antibodies/complement on RBCs (e.g., IgG in warm AIHA; C3d in cold AIHA).

Question 8

First-line treatment for warm AIHA?

Answer 8

Corticosteroids (e.g., prednisolone).

Question 9

Why does G6PD deficiency cause oxidative haemolysis?

Answer 9

Lack of G6PD → ↓NADPH → ↓reduced glutathione → RBC vulnerability to oxidative stress (e.g., fava beans, infections).

Question 10

Classic blood film finding post-crisis?

Answer 10

Heinz bodies (denatured Hb) and bite cells.

Question 11

What is the EMA binding test used for?

Answer 11

Diagnoses HS by detecting reduced band 3 protein via flow cytometry.

Question 12

How does HPLC aid in haemolytic anaemia diagnosis?

Answer 12

Identifies abnormal Hb variants (e.g., HbS, HbC) and quantifies Hb fractions.