haematology - acquired haemolytic anaemias Flashcards
classification of acquired haemolytic anaemias
autoimmune (Coomb’s +ive)
- warm
- cold
- paroxysmal cold haemoglobinuria
non-immune (Coomb’s -ive)
- paroxysmal nocturnal haemoglobinuria
- microangiopathic haemolytic anaemia
- thrombotic thrombocytopenia purpura
- haemolytic uraemia syndrome
Coomb’s test
+ive = +ive direct antiglobulin test (DAT)
features of warm AIHA
IgG
37°C
+ Coomb’s
spherocytes
features of cold AIHA/agglutinin disease
IgM
<37°C
+ Coomb’s
Raynauds
causes of WAIHA
mainly primary idiopathic lymphoma CLL SLE methyldopa
causes of cold AIHA/agglutinin disease
primary idiopathic
lymphoma
infections (EBV, mycoplasma)
management of WAIHA
steroids
splenectomy
immunosuppression
management of cold AIHA/agglutinin disease
treat underlying condition
avoid cold
chemotherapy if lymphoma
paroxysmal cold haemoglobinuria is usually caused by
viral infection, eg. measles, syphilis, VSV
what antibodies are found in PCH
Donath-Landsteiner antibodies
what do Donath Landsteiner antibodies do
present in PCH
stick to RBCs in cold
complement mediated haemolysis on rewarming
PCH is self limiting because
self limiting as IgG mediated they dissociate at higher temp than IgM
paroxysmal nocturnal haemoglobinuria
acquired loss of protective surface GPI markers on RBCs, platelets, and neutrophils
- causes complement mediated lysis
features of paroxysmal nocturnal haemoglobinuria
morning haemoglobinuria
thrombosis
Budd-Chiari syndrome - hepatic venous thrombosis
dx of paroxysmal nocturnal haemoglobinuria
immunophenotype shows altered GPI
Ham’s test (in vitro acid-induced lysis)
treatment of paroxysmal nocturnal haemoglobinuria
iron/folate supplements
prophylactic vaccines/antibodies
monoclonal antibodies
how do monoclonal antibodies help treat paroxysmal nocturnal haemoglobinuria
prevent complement from binding to RBCs
eg. eculizumab
microangiopathic haemolytic anaemia (MAHA)
mechanical RBC destruction forms schistocytes
describe the destruction of RBCs in MAHA
forced through fibrin/pit mesh in damaged vessels
causes of MAHA
HUS TTP DIC pre-eclampsia eclapmsia Rx - usually plasma exchange
thrombotic thrombocytopenia purport (TTP)
anti-ADAMTS13 antibodies
- > long strands of VWF
- > cut up RBCs in blood vessels
symptoms of TTP
MAHA fever renal impairment neuro-abnormalities thrombocytopenia
treatment of TTP
haematological emergency
requires immediate plasma exchange
Haemolytic Uraemic Syndrome (HUS)
E. coli toxins damage endothelial cells forming fibrin mesh
damages RBCs
features of HUS
impaired renal function
MAHA
diarrhoea
affects children and elderly
TTP vs HUS
neuroabnormalities in TTP but not HUS
