Haemolysis

Question 1

What is the definition of haemolysis?

Answer 1

premature red cell destruction

Question 2

Why are red cells particularly susceptible to damage?

Answer 2

need biconcave shape to transit circulation; limited metabolic reserve and rely on glycloysis; can’t geenrate new proteins in circulation

Question 3

What is compensated haemolysis?

Answer 3

increased red cell destruction compensated by increased red cell production

Question 4

What is haemolytic anaemia?

Answer 4

decompensated haemolysis

Question 5

What are the consequences of haemolysis?

Answer 5

erythroid hyperplasia; excess red cell breakdown products

Question 6

What is the bone marrow response to haemolysis?

Answer 6

reticulocytosis; erythroid hyperplasia

Question 7

When else may reticulocytosis be seen?

Answer 7

response to bleeding; iron therapy in IDA

Question 8

how is automated reticulocyte counting carried otu?

Answer 8

ribosomal RNA is albelled with fluorochrome and fluorescent cells are counted

Question 9

What is the difference between extravascular and intravascular haemolysis?

Answer 9

extravascular- taken up by reticuloendothelial system (spleen and liver); intravascular- RBCs destroyed within the ciruclation

Question 10

Is intra or extravascular haemolysis more common?

Answer 10

extravascular

Question 11

What occurs with extravascular red cell destruction?

Answer 11

hyperplasia at site of destruction; release of protoporphyrin (unconjugated bilirubinaemia and urobilinogenuria

Question 12

What is seen with intravascular red cell destruction?

Answer 12

haemoglobinaemia; methaemalbuminaemia; haemoglobinuria; haemosiderinuria

Question 13

What is seen with haemoglobinuria?

Answer 13

pink urine; turns black on standing

Question 14

What is the difference between the products of intravascualr and extravascular haemolysis?

Answer 14

intra- abnormal products whereas extravascular is normal products in excess

Question 15

What are the causes of intravascular haemolysis?

Answer 15

ABO incompatibility; G6PD deficiency; severe flaciparum malaria (blackwater fever); PNH; PCH

Question 16

What is seen on blood film with membrane damage?

Answer 16

spherocytes

Question 17

Waht is seen on blood film with mechanical damage?

Answer 17

red cell fragmnets

Question 18

What is seen on blood film with oxidative damage?

Answer 18

Heinz bodies

Question 19

How else can haemolysis be classified?

Answer 19

by red cell defect: 1- premature destruction of normal RBCs; abnormal cell memrbane; abnormal red cell maetabolism; abnormal Hb

Question 20

What are the causes of immun mediated haemolysis?

Answer 20

autoimmune haemolysis; alloimmune haemolysis

Question 21

What are the 2 types of autoimmune haemolysis?

Answer 21

warm and cold

Question 22

Waht antibodies are seen with warm AI haemolysis?

Answer 22

IgG

Question 23

What antibody is seen with cold AI haemolysis?

Answer 23

IgM

Question 24

What are the causes of warm AI haemolysis?

Answer 24

idiopathic; AI (eg SLE); lymphoproliferative disorders (CLL); drugs (penicillins); infections

Question 25

What are the causes of cold AI haemolysis?

Answer 25

idiopathic; infections (EBV, mycoplasma); lymphoproliferative disorders

Question 26

What is hte purpose of direct commbs test?

Answer 26

identifies antibody and complement cound to own red cells

Question 27

What is used in a direct coombs test?

Answer 27

patients RBCs (coated with IgG and complement)and mouse anti-human IgG

Question 28

What are hte causes of alloimmune haemolysis?

Answer 28

haemolytic transfusion reaction; haemolytic disease of the newborn

Question 29

What is the difference between the antibodies and haemolysis seen with haemolytic transfusion reactions?

Answer 29

immediate- IgM and intravascular; delayed- IgG and extravascular

Question 30

What are the causes of mechanical red cell destruction?

Answer 30

DIC; haemolytic uraemic syndrome (E.coli O157); TTP; leaking heart vlave; infection eg malaria

Question 31

what is microangiopathic haemolytic anaemia?

Answer 31

red cell fragmentation as a result of mechnical damage from damaged endothelial cells

Question 32

What is seen on blood film with burns related haemolysis?

Answer 32

microspherocytes

Question 33

What causes burns realted haemolysis?

Answer 33

red cells are sheared as they pass through damaged capillaries- only severe burns

Question 34

What are the causes of acquired membrane defects?

Answer 34

liver disease e.g Zieve's syndrome; vitamin E deficiency; paroxysmal nocturnal haemoglobinuria

Question 35

What is the triad in Zieve's syndrome?

Answer 35

haemolysis; alcoholic liver disease and hyperlipidaemia;

Question 36

What is seen on blood film with Zieve's syndrome?

Answer 36

anaemia; polychromiatic macrocytes; irregularly contracted cells

Question 37

What is the characteristic sign assocaited with paroxysmal nocturnal haemoglobinuria?

Answer 37

red urine in the morning

Question 38

What causes PNH?

Answer 38

defective surface proteins on RBC causing a reactio n with the innate immune system

Question 39

what causes hereditary spherocytosis?

Answer 39

mutation in genes related to membrane proteins that allow cell to change shape

Question 40

What drugs can cause haemolysis due to disruption of metabolic pathways of normal RBCs?

Answer 40

dapsone; salazopyrin

Question 41

What is seen on blood film with dapsone therpay?

Answer 41

keratocyte and irregularly contracted cell

Question 42

What is HbH?

Answer 42

beta4

Question 43

Why do cells contained beta4 globin chains have reduced survival?

Answer 43

beta4 is toxic and prepitates when oxidative stress

Question 44

What are Heinz bodies?

Answer 44

red cell inclusions comprised of denatured Hb normally removed by spleen eg in G6PD deficiency