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Nutrient Metabolism
Iron
27
Science
Not Applicable
03/14/2010

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Term
most common iron assessment tools
Definition
hemoglobin and hematocrit
Term
first stage of iron deficiency
Definition
iron stores in liver, spleen, and bone marrow are diminished
Term
first stage iron def. assessments
Definition
1)measure bone marrow plasma ferritin (<12mcg/L def), not a good indicator cuz depedent on other factors; better is iron content of ferritin, or % saturation of iron
Term
2nd stage of iron def.
Definition
-stores remain low and transport of iron, decreases
-circulating iron decreases
-transferrin sat decreases to <16%
-[serum iron] decreases to <50 mcg/dL
Term
transferrin saturation =
Definition
[serum iron] x 100/ TIBC
where TIBC = total iron binding capacity, normally it's 250-400 mcg/dL, levels >400 def.
Term
3rd stage of iron def.
Definition
-cellular iron becomes limiting
-free [pprotporphyrin] in erythrocytes rise
-proto >70mcg/dL RBS def.
-# of transferrin receptors on cells increase
-serum transferrin receptors increase to >8.5 mg/L
Term
4th stage of iron def.
Definition
-anemia occurs
-hemoglobin and hematocrit decrease
-[hemoglobin] <12g/dL and 13g/dL
-[hematocrit] <37 and <40%
Term
MCV
Definition
-mean corpuscular volume
-size of RBCs
=(hematocrit/RBC #) x 100
Term
MCH
Definition
-mean corpuscular hemoglobin []
-avg hemoglobin content of each RBC
= (hemoglobin/hematocrit) x 10
Term
MCHC
Definition
-mean corpusculare hemoglobin []
-amount of hemoglobin in g/dL of RBC
=(hemoglobin/hematocrit) x 100
Term
iron def. RBC features
Definition
hypochromic and microcytic
Term
hemochromatosis
Definition
-genetic disorder characterized by increases (at least 2x normal) iron absorption; body can't accurately assess iron stores; absorbed iron deposited in liver, heart and pancrease, causing organ damage
Term
hemochromatosis treatment
Definition
usually involves frequent phlebotomy (blood letting) and may require administration of deferroxamine (kelating agent)
Term
Ppl at risk for iron toxicity
Definition
those with iron-loading anemia, thalassemia, and sideroblastic anemia
Term
iron and vit. C
Definition
ascorbic acid enhances absorption
Term
iron and copper
Definition
role of copper containing ceruloplasmin is a ferroxidase, and it's needed to mobilize iron from ferritin stores
Term
iron and zinc
Definition
only affected with supplement intake (not seen from just food ingestion), 25:1 of nonheme (ferrous sulfate): zinc diminished absorption of zinc from H2O by 34%
Term
iron and vit. A
Definition
decreasing A status alters iron distribution among tissues, low plasma [retinol] are associated with decreased plasma iron and blood hemoglobin and hematocrit as well as increased hepatic iron accumulation
Term
iron and lead
Definition
lead inhibits activity of zinc-dependent aminolevulinic acid dehydratase required in heme synthesis; lead also inhibits ferrochelatase which incorporates iron into heme
Term
iron and selenium
Definition
iron def. is associated with decreased selenium -> glutathione peroxidase requires selenium and catalyzes reduction of H2O2 to H2O
Term
Why does body need to conserve iron?
Definition
Because we don't absorb enough from diet
Term
How is hemoglobin degraded?
Definition
primarily by phagocytes of reticuloendothelial system (in liver, spleen, and bone marrow)
Term
RBC's live for how long?
Definition
About 120 days; old are taken up by macrophages in spleen and degraded; reticuloendotheilial cell macrophages in bone marrow and Kupffer cells in liver
Term
Steps of RBC degredation
Definition
1) heme catabolized by heme oxygenase to biliverdin and bilirubin
2) biliverdin and bilirubin excreted into bile for excretion in feces
Term
Hemoglobin degradation leads to how much iron release?
Definition
about 20-25 mg/day
Term
Iron degradation that occurs within blood
Definition
haptoglobin and hemopexin remove and release hemoglobin and any free heme from blood, then liver does further degradation
Term
Significant hemolysis and erythropoesis decrease has what effect on iron?
Definition
1) hemolysis - iron quantity passing thru plasma can expand 6-8 x
2) decreased erythropoeisis - iron in plasma pool may decrease to as little as 1/3 of normal (ie in high altitudes)
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