Haemolytic Anaemia Flashcards
What does the MCV indicate?
It indicates the type of anaemia as it shows the relative size of RBC
What is the definition of haemolytic anaemia?
Anaemia die to shortened survival of circulating RBC due to premature destruction (can be extravascular or intravascular)
What compensatory mechanism is associated with haemolytic anaemia?
Erythroid hyperplasia= increase bone marrow activity to compensate for high RBC destruction
What is the difference between extravascular or intravascular haemolysis?
Extra
- destruction of RBCs by macrophages in spleen, liver and bone marrow due to antibodies
- Normal plasma Hb due to no haemoglobin leaking into circulation
Intra
- RBC lysis in circulation and release products to circulation
- complement activated
- haemoglobinaemia + haemoglobinuria + urine haemosiderin
What are the features of haemolytic anaemia?
Due to increased RBC destruction: high LDH (inside RBC to be used as energy source) Low haptoglobin (due to scavenging Hb degradation productions) High bilirubin Positive DAT High MCV Blood film: -spherocytes -polychromasia -RBCs fragments
Due to increase RBC production:
- high reticulocytes
- erythroid hyperplasia in BM
What is the difference between the direct and indirect anti globulin test?
What are the tests used for?
Direct:
Patient RBC coated in antibody and anti-human globulin
Indirect:
Patient plasma used
Used to test for haemolysis antibodies which could be causing the anaemia
What are the main types of HA?
Hereditary:
-abnormalities of RBC interior
I.e. Enzyme defects (add)
-haemoglobinopathies
RBC membrane abnormalities
- hereditary spherocytosis
- Hereditary elliptocytosis
Acquired: Hypersplenism Antibodies Mechanical trauma Infections Toxins Drug induced
What is the most common enzymatic disorders of HA? Why is this disorder associated with HA?
G6PD deficiency
Metabolic enzyme involved in pentose phosphate pathway= important for RBC metabolism
Protects RBC from ROS due to being involved in forming GSH which acts to convert free radicals to water under normal circumstances
Only source of NADPH
What precipitates HA in G6PD deficiency?
Drugs i.e. primaquine, sulphonamides, aspirin, quinine
Infections
Favs beans
How is G6PD diagnosed?
High LDH Retix Low haptoglobin DAT -ve i.e. indicates non-immune haemolysis Blood film: -blister cells -bite cells = due to damage by free radicals -Heinz bodies -non-spherocytic haemolytic anaemia
Why is an enzyme assay not done in an acute crisis?
False high of G6PD (look up why)
How is G6PD treated?
Prevent precipitating factors
Blood transfusion
Folic acid
Splenectomy
What AR enzyme disorder can cause HA?
Pyruvate kinase deficiency
What are the physiological and clinical consequences of pyruvate kinase deficiency?
Reduced ATP production in RBCs which causes rigidity
Variable anaemia
Gall stones and jaundice
How is pyruvate kinase deficiency diagnosed and treated?
Enzyme assay
Folic acid to treat symptoms
Splenectomy