Iron Metabolism And Microcytic Anaemia Flashcards
What are the forms of Microcytic anaemia
T : thalassemia
A : anaemia of chronic disease (sometimes)
I : iron deficiency
L : lead poisoning
S : sideroblastic anaemia
What is important about the body’s response to iron
The body has no way of extracting or excreting iron
What form does Iron need to be in for it to be absorbed
The ferrous form
Fe2+
What is the ferrous and the ferric form of iron
Ferric = Fe3+
Ferrous = Fe2+
Where does iron absorption occur
In the duodenum and the upper Jejunum (the early small intestine)
What are the forms of iron in food and which would be more readily absorbed
Non-haem and haem sources of iron
Haem = liver, kidney, beef
Non-haem = fortified cereals, raisins, beans
What form does iron need to exists in the body
Cannot be in the free form
Needs to be chelated (bound to a complex)
What factors could increase the dietary requirements of irons
Menstrual losses
Endurance running
Haemorrhage
Inflammatory bowel disease (as iron would be absorbed here)
What are the iron daily requirements
Men : 8.7mg
Women : 14.8mg
What are the three regulators of iron
Diet
Store
Bone marrow
What do the duodenal crypt cells do
Sense the status of iron through transferrin and the gene complex
How would iron be absorbed in the apical cells
Fe3+ reduced to fe2+ (so can be absorbed)
Enters through the DMT1
Transferred to ferritin
Ferritin can go to ferroportin
Ferroportin can be inhibited by hepcidin
Hephaestin oxidises fe2+ back to fe3+
Transported as transferrin
How would iron be taken up in the cells
From dietary uptake
Transferrin (containing the fe3+) attaches to the transferrin receptor
Moves in (Endocytosis)
To the endosome
Released by the acidic micro environment
Goes out the DMT1 and reduced to fe2+ (in the cytosol)
Goes to ferritin, the ferroportin or the mitochondria
What is iron used for in the mitochondria
Cytochrome enzymes
What is ferritin
Store of iron in the cells
What is ferroportin
Transports iron out the cell
What is transferrin
Binds to iron and allows it to be transported in the blood
What is haemosiderin
What excess iron is stored in
Clumps of ferritin, denatured protein and lipids
Stored in macrophages in the liver and spleen mainly
What is the difference between ferritin and haemosiderin
Ferritin = soluble
Haemosiderin = insoluble clumps of ferritin, denatured protein and lipids
Builds in the macrophages in the liver and spleen
What factors have a negative impact on the absorption of non-haem iron
Tannins (from tea)
Antacids (gaviscon)
Phytates (chapattis, pulses)
Fibre
ALL CAN BIND TO THE NON-HAEM IRON IN THE SMALL INTESTINE AND WOUOD REDUCE ITS ABSORPTION
What factors have the positive influence of the non-haem iron absorption
Vitamin c
Citrate
Reduces to ferrous form
Stops formation of the insoluble iron compounds
What cells take up the iron for it to be recycled
Macrophages
Mainly splenic and Kupffer cells
What happens to the iron when the red blood cells have been broken down by the macrophages
Iron released and exported in the blood as transferrin
Or
Taken up by the ferritin stores in the cell
What other protein interacts with the transferrin receptor (so that iron can be taken up by the cells)
High iron protein (HFE)
