haemolysis

Question 1

what is haemolysis

Answer 1

premature destruction of red cells

Question 2

2 types of haemolysis

Answer 2

compensated

uncompensated

Question 3

what is compensated haemolysis

Answer 3

increased red cell destruction
WITH
increased red cell production
HB is MAINTAINED

Question 4

what is uncompensated haemolysis

Answer 4

haemolysis
no increase in RBC production
LOW Hb

Question 5

physiological consequences of haemolysis

Answer 5

erythroid hyperplasia (increased RBC production from bone marrow - reticulocytosis)
excess RBC breakdown products (eg bilirubin)

Question 6

2 sites of haemolysis

Answer 6

extravascular (more common)

intravascular

Question 7

what is extravascular haemolysis

Answer 7

RBCs are engulfed by spleen and liver

Question 8

what is intravascular haemolysis

Answer 8

red cells destroyed within circulation

Question 9

breakdown products found in extravascular

Answer 9

NORMAL products in excess (from porphyrin ring)
unconjugated bilirubin
urobilinogenuria

Question 10

breakdown products found in intravascular

Answer 10

ABNORMAL products 
Hb in blood not in red cells:
in circulation 
in urine (PINK then turns BLACK on standing)
methaemalbuminaemia 
haemosiderinuria

Question 11

what are causes of intravascular haemolysis

Answer 11

ABO incompatible blood transfusion (red cells attacked and broken down)
G6PD deficiency
severe falciparum malaria (blackwater fever)
paroxysmal
leaky heart valve (MAHA - red cell fragmentation)
burns

Question 12

how does G6PD deficiency cause intravascular haemolytic anaemia

Answer 12

G6PD - required for glycolysis
produces ATP, NADH (NADH produces NADPH)
all required for membrane
oxidative stress -no protection of RBC - HAEMOLYSIS

Question 13

causes of extravascular haemolysis

Answer 13

immune haemolysis (warm, cold, alloimmune)
hereditary spherocytosis
haemoglobinopathy (eg thalassaemia, sickle cell)

Question 14

signs showing haemolysis

Answer 14

jaundice 
dark urine
gall stones 
leg ulcers (poor blood flow)
hepatosplenomegaly

Question 15

investigations for haemolytic anaemia

Answer 15

FBC and blood film 
reticulocyte count (increased)
unconjugated bilirubin 
serum haptoglobin
urinary urobilogen
direct antiglobulin test
chromium labelling

Question 16

blood film in haemolysis

Answer 16

polychromasia macrocytosis (increased MCV)
spherocytes (membrane damage)
red cell fragments (mechanical damage)
Heinz bodies (oxidative damage)
sickle cells

Question 17

reticulocyte count wil be increased/decreased in haemolysis

Answer 17

increased

Question 18

what type of haemolysis has increased unconjugated bilirubin, haptoglobins and urobilinogen

Answer 18

extravascular

Question 19

what are haptoglobins

Answer 19

proteins produced by liver

binds to free Hb in circulation

Question 20

haptoglobins in haemolysis

Answer 20

low - being used up faster

if nomal, EXCLUDES haemolytic anaemia

Question 21

what is direct antiglobulin test

Answer 21

coombs test

shows agglutination of red cells if positive (confirms immune cause)

Question 22

what is chromium labelling

Answer 22

measures RBC lifespan

identifies breakdown site

Question 23

2 types of immune haemolysis

Answer 23

autoimmune

alloimmune

Question 24

what is autoimmune

Answer 24

autoimmune antibodies attacking RBCs causing extravascular haemolysis

Question 25

how is autoimmune haemolytic anaemia classified and what are the corresponding responsible antibodies

Answer 25

warm (IgG) - 37 degrees

cold (IgM) - <4 degrees

Question 26

causes of warm autoimmune haemolysis

Answer 26

idiopathic 
SLE
CLL 
penicillins
infections

Question 27

causes of cold autoimmune haemolysis

Answer 27

idiopathic
infections (EBV, mycoplasma)
CLL

Question 28

what is alloimmune haemolysis

Answer 28

triggered by:
incompatible transfusion reaction
rhesus in newborns

Question 29

antibody involved in immediate incompatible transfusion

Answer 29

IgM

Question 30

antibody involved in delayed incompatible transfusion

Answer 30

IgG