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CS2 Exam II > 24: Iron Metabolism - Schmidt > Flashcards

24: Iron Metabolism - Schmidt Flashcards

1
Q 
low serum iron
low hemoglobin
*small erythrocytes 
low hematocrit
high total iron binding capacity
A

dx: iron deficiency anemia

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

tx: oral iron supplements

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2
Q

small erythrocytes …

A

not enough iron

iron deficiency anemia

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3
Q

no free Fe________ is allowed

A

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

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4
Q

ROS production by iron and copper

A

O2 + Fe2+ —> Fe3+ and O2- (ROS)

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

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5
Q

about ______ mg/day of iron in normal diet

A

10-20

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

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6
Q

how is iron excreted?

A

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

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7
Q

intravascular hemolysis –>

A

hemoglobin in urine

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8
Q

“active iron” (3)

A

hemogloin
myogloin
cytochromes

80% of iron

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9
Q

“inactive iron” (1)

A

ferritin

20% of iorn

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10
Q

transport of active iron

A

transferrin

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11
Q

degenerated, long-term storage =

A

hemosiderin

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12
Q

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

A

enterocytes

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13
Q

how does iron get from the plasma to the RBC?

A

erythroid precursors

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14
Q

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

A

mononuclear phagocytes

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15
Q

where would you find ferritin?

A

liver iron

phagocyte iron

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16
Q

where would you find heme?

A

RBC iron

diet iron

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17
Q

where would you find transferrin?

A

iron in plasma

18
Q

draw out pattern on slide 9

A

fluxes of iron

19
Q

function DMT1

A

takes in metals with a 2+ charge

20
Q

function cytochrome B

A

changes Fe3+ to Fe2+

21
Q

how does heme enter the enterocyte?

A

heme transporter (efficient 25% makes it in)

22
Q

storage of Fe2+ and heme in the enterocytes

A

ferritin

23
Q

function ferroportin 1

A

moves iron into the body from the enterocyte

24
Q

function hephaestin

A

Fe2+ to Fe3+

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

25
Q

iron export is inhibited by _______

A

hepcidin

peptide produced by liver

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

26
Q

cells that need iron use ….

A

transferrin receptor and endocytosis

H+ ions pumped in (acidified)

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

27
Q

determines how active a cell is in iron uptake

A

number of transferrin receptor on cell membrane

28
Q

inside the cell iron binds to…

A

ferritin

high concentrations in liver, spleen, and bone marrow

29
Q

ferritin particles slowly denature to…

A

hemosiderin granules

30
Q

sign of iron overload

A

hemosiderin granules

31
Q

life of RBC ends in…

A

splenic macrophages

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

32
Q

low hepcidin =

A

high uptake

33
Q

iron uptake in body is regulated by …

A

release of iron from enterocytes

34
Q

mutations in HFE cause …

A

low hepcidin expression and iron overload

hereditary hemochromatosis

35
Q

how does iron regulatory prtn work?

A

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
Q

measures unoccupied transferrin

A

TIBC total iron binding capacity

higher the TIBC, the lower the iron stores

37
Q

measure occupied transferrin

A

transferrin saturation

higher the saturation, higher the iron stores

38
Q

best measure for body iron stores ***

A

serum ferritin

fraction of ferritin present in serum

39
Q

lower the iron stores, the _____ the protoporphyrin

A

higher

protoporphyrin is iron-free precursor of heme

40
Q

stages of iron deficiency developing into anemia (3)

A
  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
Q

3 causes of iron overload

A

blood transfusions (iron accumulates in macrophages)

slow erythropoiesis (renal failure)

hereditary hemochromatosis (10% ppl carriers)

42
Q

what would you look for in iron overload (2)

A

high transferrin saturation

hemosiderin deposits

CS2 Exam II (17 decks)

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