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Path - Haemolytic Anaemia (i) (lab tests (low haptoglobin (mops up…
Path - Haemolytic Anaemia (i)
Causes (of anaemia in general)
failure to make RBCs
BM problem/failure
replacement/hypoplasia/aplasia
by tumour/fibrous tissue
marrow fibrosis in response to
cell death (chemo, radio, other drugs)
tumour infiltration (mets)
nothing (idiopathic - primary myelofibrosis)
can be immune-mediated
can be primary or secondary
lack of haematinics (Fe, B12, folate)
dietary deficiency
malabsorption
loss
RBC loss (bleeding) or destruction (haemolyisis)
chronic disease
increased requirements (e.g. pregnancy)
intro
excess RBC breakdown (lysis) with BM compensation
compensation also occurs in bleeds
reticulocytosis
distinguished haemolytic + hypoplastic
high LDH + unconjugated bilirubin
occurs in circulation + spleen (sequestration)
can be immune (always acquired) or non-immune (congenital or acquired)
Immune
autoimmune
anti-self Igs
may occur with or without obvious trigger
lymphoma, SLE, mycoplasma infection
alloimmune
response to non/altered self
transfusion reactions, haemolytic disease of newborn, BM graft rejection
drug-associated
penicillin
dapsone (treats leprosy)
Dx = Coomb's test
direct agglutination test
wash RBCs, add anti-IgM (cold) + anti-IgG (warm)
look for phagocytosis of RBC membrane (clumping)
Non-immune
acquired
RBC fragmentation syndromes
eclampsia
DIC
sepsis
RTAs
excess thrombi, then bleeding when platelets + clotting factors are depleted
mechanical (e.g. prosthetic heart valve)
congenital
membrane defects
hereditary spherocytosis and elliptocytosis/ovalocytosis
defects in structural proteins (e.g. spectrin in cytoskeleton)
RBCs can't deform - get stuck in spleen + phagocytose prematurely
enzyme defects
G6PD
pyruvate kinase
RBCs more susceptible to damage by oxidant compounds
Hb defects
thalassaemia major + minor
sickle cell anaemia
lab tests
low Hb (most important)
low haptoglobin
mops up degenerative RBC fragments then it itself breaks down
high LDH +bilirubin (haeme breakdown)
reticulocytosis in peripheral blood
BM erythroid hyperplasia
+ve Coomb's test (if immune)
blood film (RBC morphology)
electrophoresis + molecular tests
Management
transfusion if needed
! complication: Fe overload
Fe chelation (removal) if Fe overload/haemosiderosis (pyruvate kinase deficiency)
BM transplants (being used more)
decreased life expectancy :cry:
splenectomy, then immunisation
Effects of haemolysis
anaemia
hyperbilirubinaemia (gallstones + jaundice)
increased blood transfusion requirements
extra medullary haemopoiesis (hepatosplenomegaly)
BM hyperplasia
frontal bossing (more pronounced forehead)