Anaemia and polycythaemia Flashcards
Define “anaemia”
A reduction in the amount of haemoglobin in a given volume of blood below what would be expected in comparison with a healthy subject of the same age and gender
Recall 4 MECHANISMS of anaemia
- Reduced red cell/ Hb production
- Pooling of red cells in large spleen
- Blood loss
- Reduced red cell survival
What is defective in microcytic anaemia? Recall 3 causes
Haemoglobin synthesis
Defects in haem synthesis: iron deficiency
Defects in globin synthesis: alpha thalassaemia, beta thalassaemia
What name is given to anaemia caused by abnormal haemopoiesis? What classification is it given and why?
Megaloblastic anaemia (failure of DNA synthesis) MACROCYTIC - delay in maturation of the nucleus while the cytoplasm continues to mature and the cell continues to grow
What is the most common cause of megaloblastic eryhtropoiesis?
B12 deficiency
Recall 7 possible causes of macrocytic anaemia
- Vit B12 def.
- Folic acid def.
- Recent major blood loss
- Drugs that interfere with DNA synthesis
- Alcohol toxicity
- haemolytic anaemia
- Liver disease
Why would haemolytic anaemia be macrocytic?
Number of reticulocytes increased, and they are 20% bigger than mature cells
What could be a cause of pooling of red cells in an enlarged spleen?
Portal cirrhosis
Recall 3 possible causes of normacytic normachromic anaemia
- Recent blood loss
- Failure of red cell production
- Pooling in hypersplenism
Recall 3 possible causes of rec cell production failure
- Bone marrow suppression by cancer drugs
- Bone marrow infiltration by cancer
- early stages of a deficiency (B12/FA/ renal fx)
Recall 5 hereditary causes of haemolytic anaemia
- Protein deformation
- Spherocytosis
- Sickle Cell
- Pyruvate kinase deficiency
- G6PD deficiency
Recall the aetiology of hereditary spherocytosis leading to haemolytic anaemia
- Cells lose section of membrane in spleen
- Premature removal from spleen
- Bone marrow responds by increasing activity –> polychromasia and reticlocytosis
- Cells more likely to haemolyse when osmotic pressure applied
What is G6PD essential for in erythrocytes?
Prevention of oxidant damage
Recall 3 possible extrinsic oxidants that may cause G6PD deficiency
- Drugs
- Broad beans
- Napthalene (moth balls)
Who is most at risk of G6PD deficiency and why?
Hemizygous males, as the G6PD gene is on the X chromosomes
Describe the blood film of someone with haemolytic anaemia caused by G6PD deficiency
Many irregularly contracted cells
Heinz bodies
What causes Heinz bodies?
Denatired DNA
Describe the aetiology of autoimmune haemolytic anaemia
Production of AutoIg-M which is directed at red cells
IgM recognised by splenic macrophages and phagocytosed, leading to loss of membrane and spherocytosis
Recall the 5 principles of diagnosis for haemolytic anaemia
- Normachromic
- Normacytic or macrocytic
- Morphologically abnormal red cells
- increased red cell breakdown
- Increased bone marrow activity
Recall the aetiology of biliary system complications in haemolytic anaemia
Heamolysis > bilirubin production increased > jaundice + gall stones
What 2 things might be seen on the blood film of someone with haemolytic anaemia?
Spherocytes
Increased #reticulocytes
Recall the first line of treatment for haemolytic anaemia
Corticosteroids and other immunosuppressants
What measures are elevated in polycythaemia
HCt
Hb
Red cell count
WHat is the difference between pseudopolycythaemia and true polycythaemia?
Pseudopolycythaemia - results from decreased plasma vol
True polycythaemia - results from increased red cell number
