Iron Anaemia and microcytic anaemia

Question 1

What are microcytic anaemias

Answer 1

Anaemias where erythrocytes are smaller than normal due to reduced rate of haemoglobin synthesis

Question 2

What are the causes of microcytic anaemia

Answer 2

Reduced haem synthesis

• Iron deficiency
• Lead poisoning
• Anaemia of chronic disease
• Sideroblastic anaemia

Reduced globin chain synthesis

• alpha thalassaemia
• beta thalassaemia

Question 3

Why is free, excess iron a problem

Answer 3

It is very toxic to cells

• acts as a catalyst in the fenton reaction - producing free radicals
• is deposited in organs as haemosiderin

Question 4

What are the two types of dietary iron and how do they differ

Answer 4

Haem iron - from animals, more readily absorbed

Non-haem iron - from other sources, consists of both ferric and ferrous iron and is less readily absorbed

Question 5

Where and how is non-haem iron absorbed

Answer 5

It is absorbed in the duodenum and upper jejunum

Divalent metal transport 1 facilitates ferrous iron uptake

Ferric iron is reduced to ferrous iron by reductase and then DMT1 uptakes the resultant ferrous iron

Question 6

Which substances inhibit iron absorption and which increase absorption

Answer 6

Inhibitors

• Tannins
• Phylates
• Anatacids
• Fibre

Promoters

• Vitamin C
• Citrates

Question 7

What regulates iron absorption

Answer 7

Hepcidin

Question 8

Which protein transports iron

Answer 8

Transferrin

Question 9

How is iron stored

Answer 9

As ferritin or as haemosiderin

Question 10

How can iron deficiency occur

Answer 10

• Increased blood loss from bleeding
• Increased requirements
• Inadequate dietary support
• Decreased absoprtion
• Anaemia of chronic disease

Question 11

Describe the process of cellular iron uptake

Answer 11

1. ferric iron bound transferrin binds transferrin receptor and enters cytosol via receptor mediated endocytosis
2. ferric iron within endosome relased by acidic microenvironment and reduced to ferrous iron
3. ferrous iron transported to cytosol by DMT1
4. once in cytosol, ferrous iron can be stored in ferritin, exported by ferroportin, or taken up by mitochondria for use in cytochrome enzymes

Question 12

What are the signs and symptoms of iron deficiency

Answer 12

Tiredness, pallor, reduced exercise, angina, palpitations, headaches

Pica

Cold hands and feet

Low MCV, low MCHC, elevated platelets, low serum iron

Microcytic and hypochormic RBCs and anisopoikilocytosis