Iron in health and disease Flashcards
What is the importance of iron?
Oxygen transport - reversible oxygen binding by haemoglobin
Electron transport (e.g. mitochondrial production of ATP) - ferric (Fe3+) and ferrous (Fe2+) forms
Iron is present in:
- Haemoglobin
- Myoglobin
- Enzymes e.g. cytochromes
Why is iron dangerous?
Chemical reactivity - oxidative stress and free radical production
Adaptive requirements are needed for safe transport, safe storage and regulation of iron absorption.
There is no mechanism for the excretion of iron.
Where does iron absorption mainly occur?
Mainly in the duodenum - uptake into cells of the duodenal mucosa
What is iron absorption enhanced by?
Haem vs non-haem iron (dedicated haem iron trasnporter)
Ascorbic acid (reduces iron to Fe2+)
Alcohol
What is iron absorption inhibited by?
Tannins e.g. tea
Phylates e.g. cereals, bran, nuts and seeds.
Calcium e.g. dairy produce
What is transferrin?
A protein with 2 binding sites for iron atoms
What is the role of transferrin?
Transports iron from donor tissues (macrophages, intestinal cells, hepatocytes) to tissues expressing transferrin receptors.
What is especially rich in transferrin receptors?
Erythroid marrow
What is ferritin?
Spherical intracellular protein which stores up to 4000 ferric ions (Fe3+)
What are the 3 compartments that need to be looked at when assessing a patient’s iron status?
Functional iron
Transport iron/iron supply to tissues
Storage iron
How is functional iron assessed?
Haemoglobin concentration
How is transport iron/iron supply to tissues assessed?
% saturation of transferrin with iron
- Serum iron/total iron binding capacity x 100%
- Increased in iron overload, decreased in iron deficiency
How is storage iron assessed?
Serum ferritin, tissue biopsy (rarely needed)
- Tiny amount of serum ferritin reflects intracellular ferritin synthesis - indirect measure of storage iron.
- Serum ferritin also acts as an acute phase protein so goes up with infection, malignancy, liver injury etc.
What are the consequences of negative iron balance?
Exhaustion of iron stores
Iron deficient erythropoiesis leading to falling red cell MCV
Microcytic anaemia
Epithelial changes - skin, koilonychia (spoon nails) and angular stomatitis
What is angular stomatitis?
A common inflammatory skin condition. It affects one or both corners of your mouth and causes irritated, cracked sores.
Although painful, angular cheilitis usually isn’t serious. Other names for angular cheilitis include angular stomatitis and perleche.
