haemolysis Flashcards
haemolysis?
premature red cell destruction
why particularly susceptible to damage?
biconcave shape limited metabolic reserve (rely exclusively on glucose metabolism for energy), can’t generate new proteins once in the circulation
compensated haemolysis?
increased red cell destruction compensated by increased red cell production i.e. Hb maintained
haemolytic anaemia
increased rate of red cell destruction exceeding bone marrow capacity for red cell production i.e. Hb falls
consequences of haemolysis?
erythroid hyperplasia (increased bone marrow red cell production) excess red cell breakdown products e.g. bilirubin
rely on detecting therefore the breakdown products of red cells and the increased red cell production
y
bone marrow response to haemolysis?
reticulocytosis and erythroid hyperplasia
are reticulocytes nucleated?
NO
why would a blood film in a patient with haemolysis have polychromasia?
ribosomal DNA in reticulocytes have RNA that shows blue ray appearance
are reticulocytes diagnostic of hs?
no, they are a response to bleeding, iron therapy and iron deficiency anaemia
supravital stain?
supravital stain staining ribosomal RNA
automated reticulocyte counting
ribosomal RNA is labelled with a flourochrome and fluorescent cells are counted
bone marrow erythroid hyperplasia
.
extravascular hs occurs in ?
liver and spleen
intravascular?
cells destroyed within the circulation
which is commoner - intra or extravascular?
extra
what sort of signs of extravascular would you get?
hyperplasia at sites of destruction i.e. splenomegaly or hepatomegaly
normal products are in excess
.
intravascular haemolysis
red cells destroyed in circulation, spilling their contents
4 things you see?
haemoglobinaemia, methaemalbuminaemia, haemoglobinuria (pink urine, turns black on standing, haemosiderinuria
what is methaemalbumin?
methaem binds to albumin
these are ABNORMAL products
intravascular homeless may be life threatening
when would you get intravascular haemolysis?
ABO incompatible blood transfusion, G6PD deficiency, malaria, PNH, PCH (rare)
extravascular ?
all other causes of haemolysis
investigations?
FBC, reticulocyte count, serum unconjugated bilirubin, serum haptoglobins, urinary urobilinogen
what does haptoglobin bind?
free haemoglobin
blood film might show?
mechanical damage (red cell fragments) oxidative stress (Heinz bodies) Others i.e. sickle cell disease
premature destruction of normal red blood cells. autoimmune haemolysis?
warm IgG - idiopathic, autoimmune disorders, lymphoproliferative disorders, drugs, infection
cold IgM?
idiopathic, infections, lymphoproliferative disorders
what does direct coombs test identify?
antibody bound to own red cells
alloimmune haemolysis?
Immediate IgM - predominantly intravascular
delayed IgI - predominantly extravascular
passive transfer of the antibody
haemolytic disease of the newborn
rhd, abo incompatibility, others eg anti kell
haemolytic transfusion reaction iMMediate Mintravascular. delayed Gextravascular
.
mechanical red cell destruction
DIC, haemolytic uraemic syndome, TTP, leaking heart calve, infections ie malaria
mechanical damage caused - valve related - red cell fragmentation.
MAHA - microangiopathic haemolytic anaemia
in burns related homeless
microspherocytes, red cells are sheared as they pass through damaged capillaries. only seen in severe burns
membrane defects are all very rare
ziev’s syndrome, vitamin e deficiency, PNH
zieves syndrome
haemolysis, alcoholic liver disease, hyperlipidaemia
anaemia, polychromatc macrocytes, irregularly contracted cells?
zieves syndrome
hereditary spherocytosis?
pheric red blood cells which are destroyed in the spllen
what would you see in spherocytosis
splenomegaly
g6pd deficiency -
no glutathione, no atp. haemolysis
g6pd deficiency - failure to cope with oxidative stress
y
dapsone therapy can cause keratocyte and irregularly contracted cell
in beta thalassaemia major, get bony deformities of chronic erythroid hyperplasia and marrow cavity expansion
why can g6pd deficiency cause intravascular haemolysis
involved in production of NADPH, which i.e. needed for glutathione production
