Iron Flashcards
Where is the majority of iron in the body found ?
In haem
Describe iron absorption in the duodenum?
DMT-1 transports iron into duodenal enterocyte
Ferroportin facilitates iron export from enterocyte and passes on to transferrin for transport elsewhere
Hepcidin down regulates ferroportin
Assessing functional iron?
Hb conc
Assessing transported iron?
%saturation of transferrin
Assessing iron storage?
Serum ferritin
Tissue biopsy
What is transferrin?
A protein
Transports iron from donor tissues to tissues with transferrin receptors
How do you calculate transferrin saturation?
(Serum iron/ total iron binding capacity) *100
What is halotransferrin?
Iron bound to transferrin
What is apotransferrin?
Unbound transferrin
What is normal transferrin saturation?
About 20-50%
What causes serum ferritin to increase?
Infection
Malignancy
List some disorders of iron metabolism
Iron deficiency
Iron malutilisation
Iron overload
Describe the process of anaemia of chronic disease
Increased transcription of ferritin mRNA stimulated by inflammatory cytokines -> increased ferritin synthesis
Increased plasma hepcidin blocks ferroportin mediated release of iron
Results in impaired iron supply to marrow erythroblasts
Primary cause of iron overload ?
Hereditary haemachromatosis
Secondary causes of iron overload?
Transfusional
Iron loading anaemias
What happens in hereditary haemachromatosis to cause iron overload?
Decreases synthesis of hepcidin
Increased iron absorption
Gradual iron accumulation
When does hereditary haemachromatosis generally present?
Middle aged
Clinical features of hereditary haemochromatosis?
Weakness / fatigue
Joint pains
Impotence
Potential end organ damage in hereditary haemachromatosis ?
Cirrhosis
Diabetes
Cardiomyopathy
Arthritis
Treatment of hereditary haemachromatosis?
Weekly venesection
Initially want to exhaust iron stores (ferritin <20) and then keep them under control (ferritin <50)
Treatment of secondary iron overload?
Iron chelating agents - desferrioxamine
Sources of iron overload in iron loading anaemias
Repeated red cell transfusions
Excessive iron absorption related to over active erythopoiesis
