Iron Metabolism & Clinical Implications Flashcards
What is the main site of Iron absorption in humans?
- Duodenum - ferrous iron ( of the non - heme group) is absorbed .
Outline some of the factors that promote Iron absorption.
- Acidic pH e.g HCL
- Solubilizing agents e.g sugars & amino acids
- Heme iron
- Ferrous iron form
- Ascorbic acid
- Reduced serum hepcidin levels e.g in iron deficiency
- Ineffective erythropoiesis
- Pregnancy
- Increased expression of DMT-1 in duodenal enterocytes
Outline some of the factors that inhibit iron absorption in humans.
- Antacids & other alkalis, pancreatic secretions
- Inorganic iron
- Ferric iron forms
- Phytates & other precipitating agents e g phosphates
- Increased serum hepcidin levels e.g in iron overload
- Decreased erythropoiesis
- Inflammation
- Calcium salts
- Divalent metal ions e.g lead, zinc , cobalt
- EDTA
- H. Pylori infections
- Phenolic compounds e.g tea, coffee
- Decreased expression of DMT-1 in duodenal enterocytes
Main iron regulatory hormone?
- Hepcidin - synthesized by hepatocytes.
Trigger for Hepcidin production?
Increased production of Interleukin-6 which is a pro- inflammatory cytokine.
What are some of the factors that regulate expression of hepcidin in iron homeostasis?
- Serum iron levels
- Increased erythropoietic activity e.g in thalassemias
- Inflammation
- Hypoxia
What is the Mechanism of action of Hepcidin in iron regulation?
Acts by binding to Ferroportin leading to increased degradation of the iron exporter .
Role of DMT-1 protein in the duodenal enterocytes?
Facilitates transfer of iron from the lumen of the gut across the enterocyte microvilli.
Exit of iron from the cell into the portal plasma is mediated by?
Ferroportin - at the basolateral surface .
Role of Hephaestin ( ferrioxidase ) ?
Converts ferrous to ferric iron at the basal surface , prior to binding to Transferrin .
