Haematology - Haemolytic anaemias Flashcards
(39 cards)
what are the different ways haemolytic anaemia can be classified?
- intravascular
- extravascular (removal in reticuloendothelial system)
- inhertied
- axquired
list some extravascular causes
- AI
- alloimmune
- hereditary spherocytosis (AD inheritance)
list some intravascular causes
- malaria
- G6PD and PK deficiencies
- mismatched ABO blood transfusion
- cold anti-body haemolytic syndromes
- drugs
- microangiopathic HA’s (i.e. TTP)
- paroxysmal nocturnal haemoglobinuria
what can hereditary haemolytic anaemias affect?
- membrane (cytoskeltal proteins, cation permeability)
- red cell metabolism
- haemoglobin (thalassaemia, SSD, unstable Hb variants)
what are the consequences of haemolysis?
- anaemia
- erythroid hyperplasia (inc RBC production and reticulocyte circulation)
- inc. folate demans
- susceptibility to: parvovirus B12, gallstones, iron overload, osteoporosis, hepatic siderosis
why is parvovirus such a problem?
stops production of new RBCs
if got decreased survival of RBCs need new ones ASAP
how do patients with a hemolytic disorder present clinically?
- pallor
- jaundice
- splenomegaly
- pigmenturia
- FHx
how do patients with a hemolytic disorder present in lab results?
- anaemia
- reticulocytosis
- polychromasia
- inc BR
- inc LDH
- dec haptoglobins
- haemoglobinuria
- haemosiderinuria
name 2 disorders where there is a defect in RBC membrane
- hereditary spherocytosis
- hereditary elliptocytosis
what is the problem in hereditary spherocytosis? inheritance?
- spectrin or ankyrin deficiency (problems in RBC cytoskeleton)
- B19 susceptibility and propensity to develop gallstones
how do you test for hereditary spherocytosis?
- inc. sensitivity to lysis in hypotonic saline (osmotic fragility test)
- Di-binding test
- pathology slide: lack of central pallor, extravascular haemolysis
where is the mutation in hereditary elliptocytosis?
spectrin mutation
autosomal dominant
what do you get if you are homo/heterozygous in spectrin mutation?
Homo state: hereditary pyropoikilocytosis (dangerous)
Hetero state: hereditary elliptocytosis (not very dangerous)
who does G6PD def affect? inheritance?
X-linked
clinical effects in males or homozygous females
what does G6P do?
catalyses 1st step in pentose phosphate pathway to generate NADPH
this protects the RBC from oxidative damage
clinical effects of G6PD
- neonatal jaundice
- acute haemolysis (triggered by oxidants/infection)
- chronic haemolytic anaemia
what can trigger acute haemolysis in G6PD?
- anti-malarials
- antibiotics (sulphonamides, ciprofloxacin, nitrofurantoin)
- dapsone, Vit K
- fava beans and mothballs
how does G6PD present on a pathology slide?
- bite cells
- hemi-ghosts
- nucleated RBCs
- Heinz bodies (methyl violet stain)
what are other metabolic RBC disorders and how do they appear on slide?
- pyruvate kinase def (echinocytes and spherocytes. echinocytes = hedgehog-like)
- pyrimidine 5’ nucleotide def
what are the different investigations for HA?
- Direct antiglobulin test (AI haemolysis)
- urinary haemosiderin/Hb
- osmotic fragility (spherocytosis)
- G6P +/- PK activity
- Hb separation A and F percentage (Thalassaemia)
- Heniz body stains (G6PDD)
- Ham’s test (Paroxysmal nocturnal haemoglobinuria)
- thick and thin blood films
what are the different management steps for HA?
- give folic acid
- advice precipitating factors in G6PD
- red cell transfusion
- immunisation (Hep A and B)
- monitor for complications
- cholecystectomy for symptomatic gallstones
- splenectomy if indicated
what are the criteria for splenectomy?
- transfusion dependence
- growth delay
- physical limitation (Hb < 8g/dL)
- hypersplenism
- age (not <3, but before 10)
what are the HAs that are DAT +ve/ Coombs +ve?
Coombs +ve = autoimmune HA
- Warm AI HA = most common
- cold agglutin disease
what are the features of warm AI HA?
- 37 degrees
- IgG
- spherocytes
