Iron Flashcards
enhancers of iron absorption
sugars, acids, mucin, MFP factors
inhibitors of iron absorption
alkaline, polyphenols (tannins), oxalic acid (spinach), phytic acid (prefer Zn), phosvitin (egg yolk), divalent cations
functional iron is primarily ___ iron
heme (hemo/myoglobin, heme enzymes)
transport and storage iron is ___ iron
nonheme
transport iron is referred to as:
transferrin
storage iron is referred to as:
ferritin and hemosiderin
Heme= Fe + ?
porphyrin
heme synth made from ______ and needs ___ coenzyme
glycine/succinate; B6 (PLP)
3 stages of iron absorption
1) uptake at BBM 2) transport across cell 3) transport across BLM into plasma
2 forms of nonheme:
ferrous (highly reactive), ferric (unreactive)
hepcidin binds ___
ferroportin
____% heme absorbed, __% nonheme absorbed
3-8; 23
Fe2 is transported to BL by ligands such as ____; at BL it exits thru ____
mobilferrin; ferroportin
Fe2–>Fe3 in enterocyte by a copper containing enzyme called:
hephaestin
Fe3+ binds to ___
transferrin
hepcidin deficiency causes ____
hemochromatosis (too much iron in body)
hepcidin is ___ during infections/inflammation as host defense. Why?
elevated; limit available iron to invaders
hemosiderin is aggregated ___
ferritin (too much!)
Fe2+–>Fe3+ by ___
ferritin
plasma Fe–>____ –>RBC
marrow (make RBC heme)
uptake of iron into cells depends on ___
of TfRs
why is iron needed in cell?
cytochrome in mitochondria
Fe2+–>Fe3+ in all cells except enterocyte, needs this copper containing enzyme
ceruoplasmin
for every 1 mcg/L plasma ferritin, estimate there is ___mg Fe in storage
10
best test for storage of iron?
plasma ferritin levels
storage of Fe in ____ cells is highest
reticuloendothelial
heme synth requires:
glycine, succinyl coA, PLP, Zn
highest heme source? Lowest?
beef; fish
elemental iron is inert but will become ionized in ___
stomach acid
basal losses of iron each day about ___mg for 70kg person
1
DRI panel assume about ___% absorption
18 (mixed diet)
how to find RDA?
not SDs, find value at 97.5% percentile
RDA for women doesn’t apply to:
post menopause, using oral contraceptives
vegetarians/vegans need ___x more iron than omnivores
2
blood donors need ____mg extra Fe/day
3.33
UL is set at __mg to prevent ____
45; GI distress (esp iron supplements, but apply to all sources)
why do long distance athletes need more Fe?
get foot strike hemolysis
____ppl in US have hemochromotosis
5/1000
hemochromotosis results because of mutation in ___ gene, causing ____ hepcidin
HFE; decreased
symptoms of hemochromotosis?
liver damage (cirrhosis), lose insulin secretion (pancreas damage), other tissue damage (irreversible)
how is hemochromotosis detected?
high plasma ferritin of over 200 ug/dL but no more hemoglobin
how to treat hemochromotosis?
avoid Fe, frequent phlebotomy, administer chelator to increase urine Fe losses
measuring static status:
stores (marrow, plasma ferritin), transport (plasma iron, transferrin)
measuring functional status
abnormal metabolite (Zn-protoporphyrin), function
early negative iron balance is characterized by:
lower iron stores
how many stages of iron deficiency?
3
stage one of iron deficiency is characterized by:
more apotransferrin and ^ transferrin receptors to try to ^ absorb efficiency
stage two of deficiency is called :
iron deficient erythropoiesis
stage two is characterized by :
Zn-protoporphyrin (instead of heme), fewer sideroblasts
stage three of deficiency is called:
iron deficiency anemia
stage tree characterized by:
microcytic hypochromic RBCs
nails show ____ whn iron deficient
koilonychia
