Fichas
Lecture 28 - Iron metabolism
Fichas del conjunto (27)
- 1Heme ironUsually found in meat
Most bioavailable kind
Heme shields iron from dietary chelators
5-35% absorbed - 2Non heme ironFound in fruits, veggies, eggs
Mostly Fe3 - 3Fe3Ferric iron
Abundant but low bioavailability - 4Fe2Ferrous iron
More soluble
Less available
Used in iron supplements - 5FeElemental iron
Insoluble at physiologic pH
Used to fortify foods - 6Iron enhancersReducing molecules
Amino acids
Acidic foods - 7Iron inhibitorsPhytates
Polyphenols
Phosphates and phosphoproteins
Oxalate
Zn and Ca - 8Reducing moleculesThings like vitamin C that reduce Fe3 to Fe2 and form soluble complexes
- 9Amino acidsForm soluble complexes with Fe2
Found in meat and fish - 10Acidic foodsIncreased solubility of Fe and Fe3
- 11PhytatesForm insoluble complexes with Fe2
Cereal grains and legumes - 12PolyphenolsForm insoluble complexes with Fe2
Tannins in tea and coffee - 13Phosphates and phosphoproteinsForm insoluble complexes with Fe2 and Fe3
Egg yolk - 14OxalateForms insoluble complexes with Fe2 and Fe3
Spinach - 15Zn + CaCompete with Fe
Supplements - 16Fenton reactionUnbound ferrous iron (Fe2) is toxic
Non enzymatically catalyzes the formation of hydroxide radicals
Fe2 + H2O2 = Fe3 + OH + OHdot - 17TransferrinBinds ferric iron and solubilizes it
Attenuates reactivity
Delivers it to sites of use and storage - 18Transferrin receptorBinds to the iron-transferrin complex
Mediates endocytosis and the formation of an endosome
Releases the iron-transferrin complex and is recycled to the cell surface - 19FerritinIntracellular iron storage protein
24 H or L subunits
Homopolymers only found in pathologies
Iron stored in ferritin cannot catalyze the Fenton reaction - 20HemosiderinA form of ferritin in lysosomes
Stores insoluble iron
Found in conditions of iron overload - 21Iron loss in toddlersNutritional deficiency
- 22Iron loss in adultsBleeding other than menstruation
- 23IMenstruation
- 24Iron loss in pregnant womenIncreased need
- 25Serum transferrin testPresented as total iron binding capacity (TIBC)
Reflects total levels of transferrin - 26Serum ferritin testAccurately reflects intracellular ferritin levels
Inversely proportional to TF and TFR levels
Low iron = low ferritin = high TF and TFR
High iron = high ferritin = low TF and TFR
Best test for iron deficiency anemia - 27Iron deficiency anemiaCaused by acute or chronic blood loss
koilonychias, anisocytosis, poikilocytosis, target cells
HGB < 10g /dL
RBCs can be microcytic and hypochromic