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LMP301 > LMP301 Lecture 13: Iron & Hemoglobin > Flashcards

LMP301 Lecture 13: Iron & Hemoglobin Flashcards

iron metabolism & hemoglobins

1
Q

Majority of iron comes from…

A

diet

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2
Q

dietary iron is in the form…

A

ferric

Fe3+

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3
Q

Ferric iron is insoluble…

A

in basic conditions

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4
Q

5 - 10% of iron is absorbed at…

A

the duodenum

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5
Q

What happens to iron in the stomach?

A
  • converted to Fe2+

- Fe2+ can be soluble in the basic duodenum, and thus absorbed

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6
Q

what increases iron absorption?

A
  • ascorbic acid
  • sugars
  • AA
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7
Q

What decreases iron absorption?

A
  • eggs
  • cheese
  • milk
  • veggies
  • tea
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8
Q

desquamation

A

the shedding of epithelial cells

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9
Q

Iron is lost through…

A
  • desquamation
  • menstrual flow
  • urine
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10
Q

Iron is stored in…

A
  • RBC (70%)
  • Ferritin (20%)
  • Myoglobin (5%)
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11
Q

Ferritin

A

intracellular protein that stores iron

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12
Q

__ is the transport protein for iron in the plasma

A

transferrin

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13
Q

Process of iron uptake into cells

A
  1. transferrin receptor binds transferrin holding iron
  2. endosome engulfs
  3. endosome pH changes to acidic
  4. iron is released from transferrin, and is pumped out of endosome
  5. (apo)transferrin-receptor is recycled
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14
Q

(apo)transferrin

A

transferrin without iron bound to it

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15
Q

transferrin has ____ binding sites for ___

A

2

Fe+++

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16
Q

Occupancy of transferrin sites

A

not always occupied

- only 25-50% of transferrin is normally saturated

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17
Q

What used to be an indirect way to measure transferrin concentration?

A

total iron binding capacity (TIBC)

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18
Q

Iron is an ____ element

A

essential

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19
Q

free iron is…

A

toxic

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20
Q

Iron is found complexed with…

A
  • hemoglobin
  • myoglobin
  • cytochromes
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21
Q

binding of iron to proteins occurs though…

A

heme

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22
Q

Heme

A
  • inorganic molecule

- Fe goes in the middle of the ring

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23
Q

Iron is stored as…

A
  • ferritin

- hemosiderin

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24
Q

Ferritin can bind up to…

A

4500 iron atoms

This protects cells from free iron damage

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25
Q

Hemosiderin

A

= insoluble ferritin

- release iron slowly

26
Q

1/3 of iron stores are in…

A
  • liver
  • spleen
  • bone marrow
27
Q

Iron diseases

A
  • iron deficiency (anemia)
  • iron overload
  • iron poisoning
  • chronic disease
28
Q

Iron deficiency is common in…

A

women, children, elderly

29
Q

Iron deficiency is usually associated with ___ because…

A

anemia

Iron stores are used up, so can’t make enough RBC

30
Q

causes of iron deficiency

A
  • loss of blood

- inadequate intake

31
Q

What will happen to total iron binding capacity (TIBC) when iron decreases?

A

Increases

- there are more free sites, so the capacity increases

32
Q

What is a good indicator of iron deficiency?

A

decreased serum ferritin

33
Q

biochemical test: iron deficiency

A
  • low serum iron
  • high TIBC
  • low iron saturation (< 25%)
  • high serum transferrin
  • low serum ferritin
  • less Hb
  • Hb smaller
  • Hb lighter in colour
34
Q

Iron saturation

A

ratio of ferritin:transferrin

35
Q

hypochromic Hb

A

less iron in Hb, so colour is light pink instead of red

36
Q

microcytic anemia

A

RBC becomes smaller than normal

37
Q

symptoms of iron deficiency

A
  • weakness / fatigue
  • short breath
  • incr. CO
  • pale hair & nails
  • disturbed behaviour in children
  • impaired neurological development in infants
38
Q

Treatment of iron deficiency

A
  • mild: oral supplements (take wit vit C to increase absorption)
  • anemia / chronic: erythropoietin
  • severe anemia: blood transfusion
39
Q

biochemical results of iron overload

A
  • high serum iron
  • high serum ferritin
  • low TIBC
  • high iron saturation (>50%)
40
Q

Some causes of iron overload

A
  • increased intake
  • blood transfusions
  • hereditary hemochromatosis
41
Q

AR

A

hereditary hemochromatosis

42
Q

10% of ____ carry the gene for hereditary hemochromatosis

A

northern Europeans

43
Q

Occurance of the disease (homo/hetero)

A

not all homozygous people have the disease, meaning there are factors other than genetics

44
Q

is hereditary hemochromatosis more common in men or women?

A

men

45
Q

why are women protected from iron overload?

A

periods

46
Q

symptoms of hereditary hemochromatosis is apparent by…because…

A

40 years old because the iron toxicity would have had enough time to do damage to some organs

47
Q

gene responsible for hereditary hemochromatosis

A

HFE

Mutations lead to increased absorption & storage of iron

48
Q

symptoms of hereditary hemochromatosis

A
  • fatigue
  • joint pain
  • mood swings / depression
  • bronze skin colour (liver can’t remove pigment)
  • type II diabetes (pancreas harmed by iron)
  • liver-heart-thyroid dysfunction
49
Q

Iron overload will affect…

A
  • liver

- pancreas

50
Q

diagnosis of hereditary hemochromatosis

A
  • high iron

- genetic testing for HFE gene

51
Q

Treatment for iron overload

A
  • venesection

- screen at risk relatives

52
Q

Iron poisoning is…

A

acute disorder; extreme iron overload in the body

53
Q

Iron poisoning is common in…

A

children

54
Q

symptoms of iron poisoning

A
  • nausea
  • vomiting
  • abdominal pain
  • hematemesis (vomit blood)
55
Q

treatment of iron poisoning

A

chelation with desferrioxamine

56
Q

Why is venesection not used in iron poisoning treatment?

A

don’t want to remove that much blood from children

57
Q

synthesis of Hb is stimulated by…

A

low oxygen

58
Q

3 common pathological conditions associated with Hb

A
  1. a-Thalassemia
  2. B-thalassemia
  3. sickle cell anemia
59
Q

a-Thalassemia

A
  • microcytic anemia

- low a-chain synthesis for Hb

60
Q

B-thalassemia

A
  • microcytic anemia

- low B-chain synthesis for Hb

61
Q

Sickle cell anemia

A
  • hemolytic nemia
  • affects growth development
  • E -> V mutation (on beta chain)
62
Q

Consequences of HbS

A
  • susceptible to hemolysis
  • precipitate
  • occlude blood vessel -> infarction

LMP301 (18 decks)

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