Haemolytic Anaemia

Question 1

What is haemolysis?

Answer 1

The premature breakdown of RBCs before their normal lifespan

Question 2

What is the normal lifespan of RBCs?

Answer 2

120 days

Question 3

Haemolysis can occur intravascular ie in the circulation or extra vascular ie…

Answer 3

In the reticuloendothelial system - macrophages of liver, spleen, bone marrow

Question 4

Can haemolysis be asymptomatic?

Answer 4

Yes but if bone marrow does not compensate enough, a haemolytic anaemia results

Question 5

An approach is to first confirm the haemolysis then find the cause. What questions can you ask to confirm haemolysis?

Answer 5

1) Is there increased red cell breakdown?
2) Is there increased red cell production?
3) is the haemolysis mainly extra or intravascular?
4) why is there haemolysis? ie the causes

Question 6

What suggests increased red cell breakdown?

Answer 6

Anaemia with normal or increased MCV
Increased bilirubin - unconjugated, from haem breakdown (pre hepatic jaundice)
Increased urinary urobilinogen (no increase in urinary conjugated bilirubin - so urine normal colour)
Increased serum LDH (it is released from red cell)

Question 7

Describe the symptoms/ signs seen with pre hepatic jaundice

Answer 7

Mild jaundice - lemon tinge
Stools may be very dark
Urine colour normal (it is the conjugated bilirubin that turns urine dark yellow)
No pruritis

Raised serum bilirubin
Increased urinary urobiliogen
No conjugated bilirubin present in urine

Question 8

What suggests increased red cell production?

Answer 8

Increased reticulocytes causing increased MCV

Polychromasia (high number of immature RBCs)

Question 9

How do you measure increased urobilinogen if it does not change urine colour?

Answer 9

Urine dip can identify level in urine

Question 10

How do you tell if haemolysis is mainly extravascular or intravascular?

Answer 10

Extravascular haemolysis: splenic hypertrophy and splenomegaly

Intravascular:
Increased free plasma Hb released from RBCs
Methaemalbuminaemia (haem combining with albumin)
Reduced plasma heptoglobin - mops up free Hb then removed by liver
Haemaglobinuria
Haemosiderinuria

Question 11

What is haemosiderinurea?

Answer 11

Occurs when heptoglobin binding capacity is exceeded, causing free Hb to be filtered by renal glomeruli with absorption of free Hb via renal tubules and storage in tubular cells as haemosiderin.

• detected in urine as sloughed tubular cells by Prussian blue staining, one week after onset - implies chronic intravascular haemolysis

Question 12

How is haemolytic anaemia classified?

Answer 12

Acquired

Hereditary