Haematology Flashcards
What is the mechanism of action of warfarin?
Inhibition of vitamin K epoxide reductase
Where in the body is vitamin B12 absorbed?
What factor is needed for this process?
What is the deficiency of this vitamin called?
Terminal ileum. Intrinsic factor binds to dietary vitamin B12 and allows for its absorption in the terminal ILEUM. Absence of intrinsic factor (can be due to destruction by an antibody), leads to vitamin B12 deficiency.
Pernicious anaemia
What is pernicious anaemia?
Some other causes of this deficiency?
In pernicious anemia, there’s increased production of overzealous IgA antibodies against intrinsic factor or the parietal cells.
This interferes with intrinsic factor’s ability to bind to B12. Resulting in vitamin B12 deficiency.
B12 deficiency can be due to
- Decreased dietary intake
- Impaired absorption
- Crohn’s disease: enterocytes in the terminal ileum are often damaged, so B12 can’t bind to transcobalamin to get to the target tissues.
- Gastric bypass: the ingested food passes through the stomach quickly, so even if intrinsic factor is produced, it can’t get to the food to bind B12.
What are the symptoms of Vitamin B12 deficiency?
What would you see on a blood film?
Symptoms
- Glossitis (swollen tongue)
- Neurological symptoms
Blood film - Hypersegmented neutrophils (5+ lobes)
What types of anaemia does
- iron deficiency
- folate deficiency
- B12 deficiency
cause?
Name 5 Signs and symptoms of anaemia?
What are some causes of anaemia in the elderly? Why are they more at risk?
What are the components needed to make functional red blood cells?
What are some examples of anaemias that occur because of a problem with
- Iron
- Amino acids/globins
- Blasts?
.
What is the role of
- Ferric reductase?
- Ferritin?
- Ferroportin?
- Transferrin?
Ferric reductase - reduced Fe3+ to Fe2+
Ferritin - how iron is stored, mainly in the liver. (20-30% of our iron iOS stored as ferritin, 65% as haemoglobin, the rest as haemosiderin, myoglobin etc)
Ferroportin is a transmembrane protein that transports iron from the inside of a cell to the outside of the cell. Ferroportin is the only known iron exporter.[2]
After dietary iron is absorbed into the cells of the small intestine, ferroportin allows that iron to be transported out of those cells and into the bloodstream.
Transferrin - transports Fe3+
What is haemosiderin?
Breakdown product of ferritin.
What are the causes of iron deficiency? Give examples for each category.
Inadequate diet - eg. vegan, elderly reduced appetite
Increased requirement - eg pregnancy, growth in children
Decreased absorption - eg. Crohn’s, bowel resection
Blood loss - eg. menstruation, gastro, urinary, lung
What causes increased absorption of iron? name 5.
Iron 2+
Vitamin C
What causes decreased absorption of iron? name 5.
What is the role of hepcidin?
Where is it made?
What does it bind to, and what result does this have?
What anaemia is this process related to?
Hepcidin is low when?
Master regulator of iron absorption.
Made in the liver.
Binds to ferroportin so iron can’t be absorbed
Anaemia of chronic disease, haemolysis.
What GI investigations would you do for anaemia?
FIT = faecal immunochemical test
tTG tests for coeliac disease
What are some causes of macrocytic megaloblastic anaemia?
What are some causes of macrocytic non-megaloblastic anaemia?
Pregnancy
Alcohol
Liver disease
Hypothyroidism
What investigations for B12 and folate deficiency?
Describe the stages of erythropoeisis
Where does it take place
Lifespan of a RBC?
RBC’s develop in the BONE MARROW from a common progenitor cell.
120 days
What are the components of haemoglobin?
What globin chains make up HbA, HbF and HbA2?
Haem, iron, globin.
HbA (adult) = 2 alpha, 2 beta
HbF (foetal) = 2 alpha, 2 gamma
HbA2 = 2 alpha, 2 delta
Production - what growth factors are involved in erythropoeisis and where are they made?
Removal of defective cells - where?
Growth factors - erythropoietin made by kidney. Plus GM-CSF. (granulocyte-macrophage colony stimulating factor).
Production also needs iron, Vit B12, folate, amino acids.
Defective cells are removed by macrophages in the spleen and liver. Macrphages in bone marrow prevent damaged RBS’s from entering circulation.
What enzymes are needed for metabolism of RBCs?
G6PD - protects RBCs from oxidative stress
Pyruvate kinase - for ATP production
Anaemia - definition?
Levels? Men, women.
What is haematocrit?
Why would haematocrit be low?
Reduced haemoglobin concentration below the lower limit of the reference range for age and sex.
< 130 g/L in men
< 120 g/L in women
Haematocrit (aka packed cell volume) is the ratio/percentage of red blood cells in the blood. Haematocrit can be reduced because of low RBCs, high plasma, or both.