24: Iron Metabolism - Schmidt

Question 1

low serum iron
low hemoglobin
*small erythrocytes 
low hematocrit
high total iron binding capacity

Answer 1

dx: iron deficiency anemia

also observe SOB, dizziness, and a sore tongue
pallor and tachycardia

tx: oral iron supplements

Question 2

small erythrocytes …

Answer 2

not enough iron

iron deficiency anemia

Question 3

no free Fe________ is allowed

Answer 3

Fe2+/3+

Fe3+ is associated with ROS and useless

iron needs to be controlled at all times, but is very useful for binding oxygen and transferring electrons

Question 4

ROS production by iron and copper

Answer 4

O2 + Fe2+ —> Fe3+ and O2- (ROS)

H2O2 + Fe2+ —> Fe3+ and HO and HO- (ROS)

Question 5

about ______ mg/day of iron in normal diet

Answer 5

10-20

plants (Fe3+ not really usable) and animals (heme-bound) contain iron

Question 6

how is iron excreted?

Answer 6

there is no mechanism of iron excretion - we are built to conserve it

iron should be bound to prtn all the time

also have sloughing off of iron-containing cells in the intestine and kidney

Question 7

intravascular hemolysis –>

Answer 7

hemoglobin in urine

Question 8

“active iron” (3)

Answer 8

hemogloin
myogloin
cytochromes

80% of iron

Question 9

“inactive iron” (1)

Answer 9

ferritin

20% of iorn

Question 10

transport of active iron

Answer 10

transferrin

Question 11

degenerated, long-term storage =

Answer 11

hemosiderin

Question 12

how does iron in the diet get to be in the plasma?

Answer 12

enterocytes

Question 13

how does iron get from the plasma to the RBC?

Answer 13

erythroid precursors

Question 14

how does iron get to be in a phagocyte from RBC?

Answer 14

mononuclear phagocytes

Question 15

where would you find ferritin?

Answer 15

liver iron

phagocyte iron

Question 16

where would you find heme?

Answer 16

RBC iron

diet iron

Question 17

where would you find transferrin?

Answer 17

iron in plasma

Question 18

draw out pattern on slide 9

Answer 18

fluxes of iron

Question 19

function DMT1

Answer 19

takes in metals with a 2+ charge

Question 20

function cytochrome B

Answer 20

changes Fe3+ to Fe2+

Question 21

how does heme enter the enterocyte?

Answer 21

heme transporter (efficient 25% makes it in)

Question 22

storage of Fe2+ and heme in the enterocytes

Answer 22

ferritin

Question 23

function ferroportin 1

Answer 23

moves iron into the body from the enterocyte

Question 24

function hephaestin

Answer 24

Fe2+ to Fe3+

need to be in 3+ form for transport in the body, travels bound to transferrin

Question 25

iron export is inhibited by _______

Answer 25

hepcidin peptide produced by liver under stress infection, released to limit iron available (microbes need it to reproduce)

Question 26

cells that need iron use ....

Answer 26

transferrin receptor and endocytosis H+ ions pumped in (acidified) DMT1 shuttles iron (Fe2+) out of endosome into the cell

Question 27

determines how active a cell is in iron uptake

Answer 27

number of transferrin receptor on cell membrane

Question 28

inside the cell iron binds to...

Answer 28

ferritin high concentrations in liver, spleen, and bone marrow

Question 29

ferritin particles slowly denature to...

Answer 29

hemosiderin granules

Question 30

sign of iron overload

Answer 30

hemosiderin granules

Question 31

life of RBC ends in...

Answer 31

splenic macrophages macrophages take up the iron; hemolytic disorder leads to accumulation of ferritin and hemosiderin in macrophages

Question 32

low hepcidin =

Answer 32

high uptake

Question 33

iron uptake in body is regulated by ...

Answer 33

release of iron from enterocytes

Question 34

mutations in HFE cause ...

Answer 34

low hepcidin expression and iron overload | hereditary hemochromatosis

Question 35

how does iron regulatory prtn work?

Answer 35

low iron - binds and blocks high iron - Fe2+ binds instead and translation of iron related gene continues regulated on translational level with iron response element within gene

Question 36

measures unoccupied transferrin

Answer 36

TIBC total iron binding capacity higher the TIBC, the lower the iron stores

Question 37

measure occupied transferrin

Answer 37

transferrin saturation higher the saturation, higher the iron stores

Question 38

best measure for body iron stores ***

Answer 38

serum ferritin fraction of ferritin present in serum

Question 39

lower the iron stores, the _____ the protoporphyrin

Answer 39

higher protoporphyrin is iron-free precursor of heme

Question 40

stages of iron deficiency developing into anemia (3)

Answer 40

1. iron depletion - serum ferritin falls 2. deficient eryhtropoiessi - hemoglobin still normal, but protoporphyrin levels up, transferrin saturation falls 3. iron deficiency anemia - hypochromic (low hemoglobin), microcytosis

Question 41

3 causes of iron overload

Answer 41

blood transfusions (iron accumulates in macrophages) slow erythropoiesis (renal failure) hereditary hemochromatosis (10% ppl carriers)

Question 42

what would you look for in iron overload (2)

Answer 42

high transferrin saturation | hemosiderin deposits