Microcytic Anaemia Flashcards
What causes a Microcytic Anaemia?
A Deficient Haemoglobin Synthesis (cytoplamsmic defect)
What can cause a Haem group deficiency?
- Lack of Iron for Erythropoiesis.
- Problems with porphyrin synthesis.
What causes a Globin subunit Deficiency?
Thalassaemia (trait, intermedia, major)
What kind of anaemia causes the prophyrin ring not to be synthesised?
A sideroblastic anaemia.
What are the Causes of a Microcytic anaemia?
TAILS
- Thalassaemias
- Anaemia of Chronic disease
- Iron Deficiency anaemia
- Lead poisoning
- Sideroblastic anaemia
What is a sideroblastic anaemia?
Excess iron buildup in mitochondria due to failure to incorporate iron into haem.
- Can be hereditary or aquired (lead poisoning, MDS, alcohol excess)
- Causes a problem with Porphyrin synthesis.
What is the most common cause of Microcytic anaemia?
Iron Deficiency.
What is An anaemia of chronic disease and how does it cause a lack of iron for erythropoiesis?
IL-6 is released due to chronic diseases and increases production of Hepcidin.
Hepcidin down regulates ferroportin expression, reducing the iron absorption and precipitating anaemia of chronic disease.
What are some causes of Iron deficiency?
- Insufficient intake to meet physiological needs (more common in women and children due to greater requirements.)
- Losing too much - Bleeding
- Nor absorbing enough - malabsorption (coeliac disease not so common)
what colour are cells in a microcytic anaemia?
They are hypochromic (lacking in colour)
- as they contain little Hb.
What is circulating Iron bound to in the bloodstream?
transferrin
Where does Transferrin transport Iron to and from?
From Donor tissues (Macrophages, intestinal cells and hepatocytes)
Towards tissues expressing transferrin receptors (Esp. erythroid marrow)
What does % Iron T-Saturation measure?
Measures Iron supply.
- Reduced in Iron deficiency and Anaemia of chronic disease.
- Increased in Genetic Haemachromatosis.
How is Iron stored in the Liver?
In ferritin.
can store up to 4000 ferric ions.
What dose a serum ferritin measurement tell us?
Indirect measure of iron in storage.
- it reflects the intracellular ferritin synthesis in response to iron status of the host.
How does Anaemia of chronic disease reduce the supply of iron to pathogens?
- Inflammatory cytokines result in increased transcription of ferritin mRNA
- Ferritin synthesis is increased
- Inflammatory cytokines also result in increased plasma hepcidin - blocks ferroportin-mediated release of iron
- Results in impaired iron supply to marrow erythroblasts and eventually hypochromic red cells
What are the sequential consequences of negative iron balance?
- Exhaustion of iron stores (ferritin falls)
- Iron deficient erythropoiesis (MCV falls)
- Microcytic anaemia develops
- Epithelial changes (effects elsewhere) - skin, koilonychia, angular chelitis
What are spoon-shaped nails called?
Koilonychia
What is a low MCV value?
<80fL
What is a Low MCH value (seen in Microcytic anaemia)?
<27 pg
“hypochromic”
What is the inital management of an Iron Deficiency anaemia?
- Improve iron intake.
- Review other medications e.g. anticoagulants, PPIs
When is IV Iron considered?
when oral is unsuccessful. (poor tolerance, poor compliance, malabsorption issues, specific situations e.g renal impairment)
What are some side effects of oral Iron?
Constipation, Nausea and Vomiting, Abdominal pain, dark stools.
How is anaemia of chronic disease managed?
Treating the underlying cause.
