Iron Metabolism Flashcards
How can we alter the amount of iron in out bodies?
We have no method for excretion of Iron and so we must alter how much we absorb. For a typical adult this is 1-2mg a day.
Where is the majority of active iron found in our bodies?
In haemoglobin and accounts for approx 200mg. 130mg is stored in myoglobin.
Name the two iron stores in the body.
Ferritin and Haemosiderin
What is ferritin?
This is a soluble iron store which is found in the blood and can be measured with blood tests.
What is the name of the condition when iron is deposited in many organs of the body?
Haemosiderosis.
What is Haemosiderin?
This forms when there is either local or systemic iron excess and has a yellow/brown colour.
How do our iron needs change throughout pregnancy?
When we pass 20 weeks gestation, our iron needs increase massively.
What is the best source of iron from our diet? Haem or non-haem?
Haem iron is the best source of iron and we get it mainly from meat. Vegetarians rely a lot on non-haem iron.
What must happen to non-haem iron before it can be transported across the intestinal epithelium?
The fe3+ ion must be converted to fe2+ before it can be absorbed.
State the role of stomach acid in iron metabolism.
Stomach acid reduces fe3+ to fe2+ and it then binds to transferrin and is transported into the enterocytes.
What is the fate of iron that has been absorbed?
It can be stored in enterocytes as transferrin or it is released into the blood stream and then stored in the liver or used for haemoglobin.
What is ferroportin?
This transports iron out of cells.
If taking iron supplements, which drinks are best to be taken with?
Vitamin C increases iron absorption. Tea and antacids neutralise the stomach acid and so reduce the potential absorption.
What are erythroid cells?
These cells have many transferrin receptors and take up iron.
How is iron from haemoglobin recycled?
When the erythrocyte nucleus is engulfed by the macrophages it is located in an erythroid cell island and so some is reused for the next generation of erythrocytes.
What is hepcidin?
This is a negative regulator for iron absorption and degrades ferroportin.
In what situations will the synthesis of hepcidin increase/decrease?
In iron overload its synthesis will increase and when there is high erythrocyte synthesis production will decrease.
What form does the majority of iron stored in the liver found in? What is the rest?
95% of Iron stored in the liver is in the form of ferritin. The remainder is Haemosiderin found in kupffer cells.
Name two causes of iron deficiency.
Poor absorption/ intake of iron. Increased use of iron e.g.physiologically pregnancy or pathologically bleeding.
How will rbc present on a micrograph if there is iron deficiency?
There will be a larger area of pallor due to haemoglobin deficiency.
State two major symptoms of iron deficiency.
Classic anaemia symptoms: pallor, tiredness
Epithelial changes: cracked lips and poor nails.
What is the most commonly used measure of body iron?
Serum transferrin. This correlates with the amount of iron in body stores and so is generally the most accurate as it does not vary with eating.
What can cause an increase in ferritin that’s not increased iron?
Acute and chronic inflammation, malignancy and liver disease.
What does it tell us if a blood test returns wi decreased ferritin?
This indicates iron deficiency.
What is the common supplement used for iron deficiency?
Ferrous sulphate.
When is IM iron given?
Before surgery or during labour if iron levels need to be raised quickly.
What is the problem with excess iron in the body?
If the capacity of transferrin to bind oxygen is exceeded then this leads to free iron in the blood. This is very dangerous as it can lead to free radical formation.
What is haemochromatosis?
Haemochromatosis is where iron is deposited in the tissues and this leads to damage and pigmentation.
What is hereditary haemochromatosis?
This is an autosomal recessive condition affecting how genes interact with hepcidin
When can Haemosiderosis commonly occur?
After a blood transfusion.
