Haemolysis Flashcards
what is haemolysis?
premature destruction of red cells
why does bilirubin increase in haemolysis?
RBC breakdown breaks haemoglobin into its constituent parts
porphyrin ring breakdown eventually forms bilirubin
why are red cells susceptible to damage?
no nucleus - cant generate new proteins
limited metabolic reserve - rely on glycolysis
biconcave shape
what are Hb levels like in compensated haemolysis and why?
normal
haemolysis is compensated by inc RBC production
another term for decompensated haemolysis?
haemolytic anaemia
what is Hb like in haemolytic anaemia and why?
low
inc rate of haemolysis exceeds BM’s capacity for RBC production
what does the bone marrow do in response to haemolysis?
undergoes erythroid hyperplasia (inc BM red cell production) to produce more reticulocytes
what can you measure to look for haemolysis?
reticulocytes
breakdown products eg bilirubin
reticulocytosis is diagnostic of haemolysis T or F
F
present in bleeding, iron therapy etc
what cells are polychromatic and why?
reticulocytes
contain RNA
where is the main site of destruction in extravascular haemolysis
liver and spleen
where is the main site of destruction in intravascular haemolysis?
circulation
is extravascular or intravascular haemolysis more common?
extravascular
what happens to the organs at the site of destruction in extravascular haemolysis?
undergo hyperplasia
eg splenomegaly
what does the release of protoporphyrin in extravascular haemolysis cause?
unconj bilirubinaemia
jaundice
gallstones
urobilinogenuria
what haemolysis type is controlled and therefore does NOT have abnormal breakdown products?
extravascular haemolysis
pathophysiology of intravascular haemolysis?
red cells spill their contents into the bloodstream
free Hb in blood and urine
Hb breakdown products combine with other substances to form toxic products in blood and urine
colour of urine in haemoglobinuria?
pink, turns black on standing
what is the cause methaemalbuminaemia?
Hb breakdown product methaem forms a complex with albumin in the blood
causes of intravascular haemolysis?
ABO incompatible blood transfusion
G6PD dfeficiency
malaria
Ix haemolysis
FBC blood film reticulocyte count serum unconj bilirubin serum haptoglobins urinary urobilinogen
what should urine be checked for in haemolysis?
urobilinogen
unconjugated or conjugated bilirubin increases in haemolysis?
unconjugated
why is haptoglobin checked?
haptoglobin binds prehaemoglobin so if Hb is low from haemolysis this will also be low
genetic causes of haemolysis
haemoglobinopathies
G6PD deficiency
thalassaemia
sickle cell (look for HbS)
spherocytes indicate…
membrane damage
heinz bodies indicate..
oxidative damage
what factors can lead a red cell to haemolyse?
premature destruction
dysfunctional cell membrane
abnormal metabolism
abnormal Hb
most common form of autoimmune haemolysis?
warm autoimmune haemolytic anaemia
what antibody is involved in warm autoimmune HA?
IgG
what antibody is involved in cold autoimmune HA?
IgM
causes of warm autoimmune HA?
idiopathic autoimmune disorder eg SLE chronic lymphocytic leukaemia drugs eg penicillins infection
causes of cold autoimmune HA?
idiopathic
infections eg EBV/mycoplasma
lymphoproliferative disorders
what happens in a direct coombs test?
given antibodies to see if they bind to your own red cells (which causes agglutination)
pathophysiology of autoimmune HA?
producing antibodies against your own RBC antigens
causes of alloimmune haemolysis?
transfusion reaction
haemolytic disease of newborn due to rhesus/ABO cause
if a transfusion reaction IMMEDIATELY causes haemolysis, what kind of haemolysis will it be and what antibody will cause it?
IgM
intravascular haemolysis
if a transfusion reaction causes a DELAYED haemolysis, what kind of haemolysis will it be and what antibody will cause it?
IgG
extravascular
causes of acquired haemolysis from MECHANICAL destruction?
coagulation disorder
HUS (e.coli 0157)
leaky heart valve
infections eg malaria
microspherocytes are a sign of..
burns related haemolysis (sheared as they pass through damaged capillaries)
name the triad of symptoms for zieve’s syndrome
haemolysis
alcoholic liver disease
hyperlipidaemia
G6PD deficiency most often affects which members of the population?
MALES
consequences of G6PD deficiency?
cant generate ATP
cant cope with oxidant stess
bony deformities, chronic anaemia and erythroid hyperplasia…
beta thal major
what is alloimmunity?
immune response to a foreign antigen
parent had splenectomy, child has splenomegaly…
hereditary spherocytosis
