haemolytic anaemia

Question 1

definition

Answer 1

Haemolytic anaemia encompasses a number of conditions that result in the premature destruction of RBCs. Common causes include autoantibodies, medications, and underlying malignancy, but the condition can also result from a number of hereditary conditions, such as haemoglobinopathies.

Question 2

types

Answer 2

Acquired haemolytic anaemia: immune or non-immune

1. Immune (direct antiglobulin test often positive):
   - Warm antibody autoimmune haemolytic anaemia: antibody (usually IgG) binds most avidly at core body temperature. Associated with underlying diseases such as SLE, lymphoma, and chronic lymphocytic leukaemia.
   - Cold antibody autoimmune haemolytic anaemia: antibody binds RBC at temperature below body temperature. (often IgM, but may be IgG). Can be idiopathic, or associated with infection or malignancy.
   - Drug-induced immune haemolytic anaemia.
   - Alloimmune haemolytic anaemia: haemolytic disease of the newborn or transfusion reaction.
2. Non-immune (direct antiglobulin test negative):
   - Infection: malaria, babesiosis, bartonellosis.
   - Bacterial toxins: Clostridium perfringens infection.
   - Drug-induced (by non-immune mechanism).
   - Trauma: microangiopathic haemolysis such as DIC, thrombotic thrombocytopenic purpura, haemolytic uraemic syndrome, eclampsia, HELLP syndrome (haemolysis, elevated liver enzymes, low platelet count) in pregnancy; mechanical prosthetic heart valve; march haemolysis.
   - Membrane disorder (acquired): paroxysmal nocturnal haemoglobinuria, liver disease.
   - Thermal injury.
   - Osmotic lysis.
   - Hypersplenism.

Congenital haemolytic anaemia
1. Red cell membrane disorders:
Hereditary spherocytosis
Elliptocytosis
Pyropoikilocytosis

2. Red cell enzyme defects:
   Glucose-6-phosphate dehydrogenase deficiency
   Pyruvate kinase deficiency
3. Haemoglobinopathies:
   Sickle cell anaemia
   Thalassaemia

Question 3

symptoms and signs

Answer 3

pallor
fatigue
SOB
dizziness
jaundice
splenomegaly

Question 4

risk factors

Answer 4

• autoimmune disease
• lymphoproliferative disorders
• prosthetic heart valve
• sickle cell anaemia
• G6PD deficiency + expsosure to napthalene or fava beans
• family history of hemoglobinopathy
• thermal injury

Question 5

investigations

Answer 5

1st investigations:

• FBC
• MCHC
• reticulocyte count
• peripheral smear
• unconjugated (indirect) bilirubin
• serum LDH => would be raised
• haptoglobin
• urinalysis => Haemoglobinuria is present in intravascular haemolysis

others:

• direct antiglobulin test (aka coombs’ test) => positive suggests immune aetiology; negative suggests non-immune aetiology
• creatinine and urea => elevated in thrombotic thrombocytopenic purpura or haemolytic uraemic syndrome
• LFTs
• Hb electrophoresis
• G6PD fluorescent spot test and spectrophotometry
• Donath-Landsteiner antibody => present in IgM/cold-immune diseases
• ANA => test for SLE cause