24: Iron Metabolism - Schmidt Flashcards Preview

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Flashcards in 24: Iron Metabolism - Schmidt Deck (42):
1

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

dx: iron deficiency anemia

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

tx: oral iron supplements

2

small erythrocytes ...

not enough iron

iron deficiency anemia

3

no free Fe________ is allowed

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

4

ROS production by iron and copper

O2 + Fe2+ ---> Fe3+ and O2- (ROS)

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

5

about ______ mg/day of iron in normal diet

10-20

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

6

how is iron excreted?

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

7

intravascular hemolysis -->

hemoglobin in urine

8

"active iron" (3)

hemogloin
myogloin
cytochromes

80% of iron

9

"inactive iron" (1)

ferritin

20% of iorn

10

transport of active iron

transferrin

11

degenerated, long-term storage =

hemosiderin

12

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

enterocytes

13

how does iron get from the plasma to the RBC?

erythroid precursors

14

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

mononuclear phagocytes

15

where would you find ferritin?

liver iron
phagocyte iron

16

where would you find heme?

RBC iron
diet iron

17

where would you find transferrin?

iron in plasma

18

draw out pattern on slide 9

fluxes of iron

19

function DMT1

takes in metals with a 2+ charge

20

function cytochrome B

changes Fe3+ to Fe2+

21

how does heme enter the enterocyte?

heme transporter (efficient 25% makes it in)

22

storage of Fe2+ and heme in the enterocytes

ferritin

23

function ferroportin 1

moves iron into the body from the enterocyte

24

function hephaestin

Fe2+ to Fe3+

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

25

iron export is inhibited by _______

hepcidin

peptide produced by liver

under stress infection, released to limit iron available (microbes need it to reproduce)

26

cells that need iron use ....

transferrin receptor and endocytosis

H+ ions pumped in (acidified)

DMT1 shuttles iron (Fe2+) out of endosome into the cell

27

determines how active a cell is in iron uptake

number of transferrin receptor on cell membrane

28

inside the cell iron binds to...

ferritin

high concentrations in liver, spleen, and bone marrow

29

ferritin particles slowly denature to...

hemosiderin granules

30

sign of iron overload

hemosiderin granules

31

life of RBC ends in...

splenic macrophages

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

32

low hepcidin =

high uptake

33

iron uptake in body is regulated by ...

release of iron from enterocytes

34

mutations in HFE cause ...

low hepcidin expression and iron overload

(hereditary hemochromatosis)

35

how does iron regulatory prtn work?

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

36

measures unoccupied transferrin

TIBC total iron binding capacity

higher the TIBC, the lower the iron stores

37

measure occupied transferrin

transferrin saturation

higher the saturation, higher the iron stores

38

best measure for body iron stores ***

serum ferritin


fraction of ferritin present in serum

39

lower the iron stores, the _____ the protoporphyrin

higher

protoporphyrin is iron-free precursor of heme

40

stages of iron deficiency developing into anemia (3)

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

41

3 causes of iron overload

blood transfusions (iron accumulates in macrophages)

slow erythropoiesis (renal failure)

hereditary hemochromatosis (10% ppl carriers)

42

what would you look for in iron overload (2)

high transferrin saturation
hemosiderin deposits