Haemolysis and Haemolytic Anaemia

Question 1

What is haemolysis?

Answer 1

the premature breakdown of red blood cells

Question 2

What is a RBC’s normal lifespan?

Answer 2

about 120 days

Question 3

Where can haemolysis occur?

Answer 3

intravascular - in the circulation

extravascular - in the reticuloendothelial system

Question 4

What is the reticuloendothelial cell system?

Answer 4

macrophages of liver, spleen and bone marrow

Question 5

What may you find on examination with haemolysis?

Answer 5

jaundice

hepatosplenomegaly

Question 6

What are the consequences of haemolysis?

Answer 6

excess red blood cell breakdown products

erythroid hyperplasia

Question 7

How would you know if there was increased red cell destruction?

Answer 7

anaemia (normal or increased MCV)
increased bilirubin (unconjugated, from haem breakdown)
increased serum lactic dehydrogenase (released from RBC)
increased urinary urobilinogen

Question 8

How would you know if there was increased RBC production?

Answer 8

increased reticulocytes

Question 9

Features of extravascular haemolysis?

Answer 9

spleno+/-hepatomegaly

Question 10

4 features of intravascular haemolysis?

Answer 10

methaemalbuminaemia
haemoglobinuria (red brown urine)
decreased plasma haptoglobin
haemosiderinuria

Question 11

What is methaemalbuminaemia?

Answer 11

some free Hb is broken down in the circulation to produce haem and globin - haem combines with albumin

Question 12

What is Coombs/antiglobulin test?

Answer 12

determines if its an immune cause of haemolysis

Question 13

What does a positive Coombs result indicate?

Answer 13

an immune cause of haemolysis

Question 14

What are the immune mediated acquired causes of haemolytic anaemia?

Answer 14

drug induced
autoimmune haemolytic anaemia
isoimmune - acute transfusion reaction, haemolytic disease of the newborn

Question 15

What are the non immune mediated acquired causes of haemolytic anaemia?

Answer 15

direct coombs test negative autoimmune haemolytic anaemia
infection
microangiopathic haemolytic anaemia

Question 16

What is autoimmune haemolytic anaemia?

Answer 16

extravascular haemolysis and spherocytosis

mediated by autoantibodies

Question 17

How is autoimmune haemolytic anaemia classified?

Answer 17

according to optimum binding temp to RBCs

warm and cold

Question 18

Describe warm autoimmune haemolytic anaemia.

Answer 18

IgG mediated
body temp
treatment: steroids, immunosuppression +/- splenectomy

Question 19

Describe cold autoimmune haemolytic anaemia

Answer 19

IgM mediated
chronic anaemia made worse by cold
treatment: keep warm

Question 20

What infection can cause acquired haemolytic anaemia?

Answer 20

malaria

Question 21

What are causes of autoimmune haemolytic anaemia?

Answer 21

idiopathic

secondary: CLL, lymphoma, drugs, infection, AI conditions e.g. SLE

Question 22

What are the hereditary causes of haemolysis?

Answer 22

enzyme defects e,g, glucose-6-phosphate dehydrogenase deficiency, pyruvate kinase deficiency

membrane defects e.g. hereditary spherocytosis

haemoglobinopathy e.g. sickle cell disease, thalassaemia

Question 23

What happens in spherocytosis?

Answer 23

less flexible red blood cells
trapped in spleen
extravascular haemolysis

Question 24

What happens in extravascular haemolysis?

Answer 24

hyperplasia at site of destruction
release of protoporphyrin –> unconjugated jaundice
normal blood products in excess

Question 25

What happens in intravascular haemolysis?

Answer 25

RBC destroyed in circulation and spill contents

abnormal blood products in excess