Hypochromic, microcytic anaemias Flashcards
Causes of microcytic anaemia
Haem deficiency
- Lack of iron for epo
- Iron deficiency (low body iron)
- Anaemia of chronic disease (normal body iron but locked away in wrong compartments)
- Congenital sideroblastic anaemia
Globin deficiency
- Thalassaemias
What is iron deficiency anaemia?
Iron deficiency is the most common cause of anaemia in the world, affecting 30% of the world’s population. This is because of the body’s limited ability to absorb iron and the frequent loss of iron owing to haemorrhage.
Causes of iron deficiency anaemia
- Not eating enough
- Losing too much - GI (tumours, ulcers, NSAIDs), menorrhagia
- Not absorbing enough - malabsorption (relatively uncommon), coeliac disease, achlorhydria
Which form of iron is most readily absorbed?
Ferrous - Ferric form is most abundant, but ferrous is more readily absorbed
What is the average daily intake of iron?
15-20 mg, 10% of which is absorbed. This can increase to 20-30% in those who are iron deficient or pregnant
What are the two groups of sources of iron?
- Haem iron - from haemoglobin and myoglobin in red or organ meats
- Non-Haem Iron - fortified cereals
How is iron stored?
Ferritin
How is iron transported?
Transferrin in the blood stream
Ferroportin from cells into the blood strea,
What does hepcidin do?
Inhibits the activity of ferroportin therefore less iron transported into the blood circulation and will stay in storeage instead.
What condition is associated with a defficiency in hepcidin?
Hereditary haemochromatosis. Occurs due to HFE mutation meaning the protein cannot relay iron levels to hepcidin so ferroportin transporters are not regulated.
What are causes of iron deficiency anaemia?
- Blood loss
- Increased demands such as growth and pregnancy
- Decreased absorption (e.g. post-gastrectomy)
- Poor intake
What are examples of blood loss that can lead to iron deficiency anaemia?
- Menorrhagia
- GI bleeding
If someone had hypochromic, microcytic anaemia, what investigation would you do?
Serum Ferritin
If someone had a microcytic hypochromic anaemia and a low serum ferritin, what would the diagnosis be?
Iron deficiency anaemia
What other iron studies could you do to aid the diagnosis of iron deficiency anaemia?
- Serum Iron levels - Decreased
- Total iron binding capacity - Raised
- Serum soluble transferrin receptors - raised
What are the three comparments for the assessment of iron status?
- Functional iron - haemoglobin concentration
- Transport iron/iron supply to tissues - % saturation of transferrin with iron
Measuring transferrin saturation measures iron supply. - Storeage iron - serum ferritin
How would you approach determining the cause of iron deficiency anaemia?
History - look for clear history of menorrhagia. If not, look for GI blood loss - colonoscopy, endoscopy, gastroscopy, sigmoidoscopy, stool microscopy etc.
If someone had iron deficiency anaemia with no obvious cause of bleeding, what would you do?
Thorough GI investigation to look for GI bleeding source