Iron Homeostasis Flashcards
How much iron exists in the body and what proportion of this exists in red blood cells?
4g in total, 3g exists in RBCs
Other than red blood cells, where does iron exist in the body?
Myoglobin Cytochromes Peroxidases Xanthine oxidase Catalases RNA reductase
Which molecule is the main storage system for iron?
Ferritin
Other than in ferritin, how can iron be stored?
Haemosiderin
Serum ferritin may be elevated in response to tissue inflammation. Why is this?
Because it is an acute phase protein
What is the name of the glycoprotein, synthesised by hepatocytes which transports iron in the plasma?
Transferrin
Normally, how saturated is transferrin with iron?
30%
In what cells are the majority of the receptors for transferrin located?
Red blood cell precursors and hepatocytes
How much iron needs to be consumed each day in the diet to replace lost iron?
1-2mg
Nutritional iron deficiency is common in the UK. T/F?
False
In what foods would you find hadm and non haem iron?
Red meat - haem iron
White meat, green veg, cereals -non haem iron
Where does iron absorption predominantly take place?
Duodenum
Non haem iron must be reduced to the ferrous form for absorption to take place. Which enzyme does this?
Cytochrome b1
Which vitamin influences iron absorption?
Vitamin c
What is the name of the transporter which transports iron into the enterocyte during absorption?
Divalent metal transporter one
What protein transports iron across the basolateral membrane of the enterocyte?
Ferroportin
What is the role of hepcidin in iron absorption?
Hepcidin binds to and degrades ferroportin and thus reduces GI iron absorption and reduces macrophage iron release
What gene is required for the synthesis of hepcidin in the liver?
HFE gene
As a general rule, for which group of patients should it always be assumed that iron deficient anaemia is related to GI blood loss until proven otherwise?
Men and postmenopausal women
Which vitamins and minerals can be deficient as a result of coeliac disease?
Folate
Iron
vitamin b12
What is the cause of hereditary haemochromatosis?
It is an autosomal recessive condition where there are abnormalities of the HFE gene which means that functional hepcidin is not produce and iron levels are too high
How saturated is transferrin with iron in hereditary haemochromatosis?
100%
What are the consequences when excess iron accumulates in various tissues due to hereditary haemochromatosis?
Cirrhosis of the liver Pancreas damage resulting in diabetes Skin bronzing Arthritis Restrictive cardiomyopathy
How is hereditary haemochromatosis treated in non anaemic patients?
Venesection
