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House Hemat > Iron Metabolism > Flashcards

Iron Metabolism Flashcards

1
Q

Iron

Transition metal

May be _____ or _____

A

2+ or 3+

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2
Q

Ferrous(__+)
Ferric(__+)

A

2

3

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3
Q

Ferrous(2+) “________”- ______an electron

Ferric(3+) “________”-_____an electron.

A

reduced; gained

oxidised; lost

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4
Q

DIETARY SOURCES OF IRON

Non Haem:
•______________-___% bioavailability
-Absorption enhanced by ——- agents e.g. ascorbic acid(maintains Fe2+),hydroquinone, lactate, pyruvate, succinate, fructose, sorbitol, and cysteine
-Inhibited by ______,———-,_______

A

Cereals, legumes,vegetables

10; reducing

tannins ,phytates, and phosphates.

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5
Q

DIETARY SOURCES OF IRON

Haem:
•
-_______
-_____% bioavailability -Haem is taken up intact.

A

meat, fish

30

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6
Q

_______mg of iron enters the body each day and most of them enter ______

Most of the iron seen in the plasma is from ________________________

Each day, approximately ____ mg of iron is lost from the body

The remaining body iron is stored, primarily in _______

A

1 to 2

haemoglobin

continuous breakdown of haemoglobin in old red cells by RE macrophages

1 to 2

hepatocytes

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7
Q

Iron functions

Oxygen carriers eg ________

Oxygen storage eg _______

Energy Production ________, _______

Other:

Liver detoxification (_________)

A

haemoglobin

Myoglobin

Cytochromes (oxidative phosphorylation); Krebs cycle enzymes

cytochrome p450

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8
Q

IRON COMPARTMENTS

The concentration of Iron in adult human body is usually ___mg/kg in males and ___mg/kg in females.

A

50

40

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9
Q

IRON COMPARTMENTS

_____ Iron compartments.

A

six

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10
Q

IRON COMPARTMENTS

HAEMOGLOBIN
molecular weight ____ Da

____% iron by weight.
1ml packed RBC contains approximately 1mg iron
Total body amount is 2-2.5gm.
Lower in (males or females?) .

A

64500

0.34

Females

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11
Q

IRON COMPARTMENTS

STORAGE IRON(FERRITIN)
Water (soluble or insoluble ?) protein –

Found in _______ cells of the body and tissue fluids.
Has an outer protein shell _____ and an _________________ core.
Can bind _________ atoms of Iron.

A

Soluble

apoferritin

iron- phosphate-hydroxide

4500-5000

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12
Q

IRON COMPARTMENTS

MYOGLOBIN IRON
Structurally similar to _____ but ______.

Present in (small or large?) amounts in all __________ muscles.

A

Haemoglobin; monomeric

Small

skeletal and cardiac

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13
Q

MYOGLOBIN IRON

__________ + ______________

A

Haem group +polypeptide chain of 150 amino acids.

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14
Q

IRON COMPARTMENTS

LABILE POOL

Iron leaves plasma and is bound to ___________ , then incorporated into ____ or other structures, or refluxes into plasma

A

membrane or cytoplasmic proteins.

heme

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15
Q

IRON COMPARTMENTS

TISSUE IRON
Heme proteins - ____,_______,______

Flavoproteins -__________, _______,_________

A

cytochromes, peroxidases, catalase

xanthine oxidase; dehydrogenases

cytochrome C reductase

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16
Q

IRON COMPARTMENTS

TRANSPORT IRON

Contains ___mg of Iron and turns over ____ times per day.

A

3

10

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17
Q

Smallest but most active compartment.is ???

A

Transport

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18
Q

_______ and _______ transport Iron in plasma and milk respectively.

A

Transferrins and lactoferrins

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19
Q

IRON ABSORPTION

Occurs in the ______
Taken up as ___ iron or _____ iron
1 – 2 mg iron are absorbed each day
Only ___% of dietary iron is absorbed

A

duodenum

ionic; haem

10

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20
Q

Dietary iron is usually in excess

T/F

A

T

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21
Q

Excess dietary iron is either ______, or __________ and shed into the gut

A

not absorbed

kept in enterocytes

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22
Q

IRON ABSORPTION CONTINUED

_____- Reduction Fe+++ to Fe++

______- Transport into cell

______- Storage in cell

______- Oxidises Fe++ to Fe+++

_______- Transport out

A

DcytB

DMT1

Ferritin

Hephaestin

Ferroportin

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23
Q

Non heme

2+ or 3+?

A

3+

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24
Q

Heme

2+ or 3+

A

2+

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25
Q

Which version is allowed into the enterocytes

2+ or 3+

A

2+

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26
Q

Acidic PH hinders or favors iron absorption ?

A

Favors

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27
Q

Iron deficiency hinders or favors iron absorption ?

A

Favors

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28
Q

Pregnancy hinders or favors iron absorption ?

A

Favors

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29
Q

Hypoxia hinders or favors iron absorption ?

A

Favors

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30
Q

Iron overload hinders or favors iron absorption ?

A

Hinders

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31
Q

Phytates hinders or favors iron absorption ?

A

Hinders

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32
Q

HEPCIDIN

_______ activity
Hepatic ______ protein
Master iron ______ hormone
Inactivates ______
Stops iron __________, therefore Iron is lost in stool when gut cells shed
Leads to ___eased gut iron absorption

A

Antimicrobial

bacteriocidal

regulatory

ferroportin

getting out of gut cells
Decr

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33
Q

HEPCIDIN

Increased production of Hepcidin is induced by inflammation via _____

Hepcidin synthesis and secretion are controlled by ___________,__________, and _________
Iron deficiency, hypoxia , and ineffective erythropoiesis.

A

interleukin 6.

HFE, hemojeuvelin, and Transferrin receptor 2.

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34
Q

Hepcidin deficiency targets the _____ and ______

A

Duodenum and spleen

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35
Q

Ferroportin
________ transmembrane segment protein

A

12 (or 10)

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36
Q

The only cellular iron exporter in vertebrates is _____

A

Ferroportin

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37
Q

Ferroportin

Present in the _______,_______,_________, and _________

A

macrophages, duodenum, hepatocytes, and the placenta

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38
Q

Ferroportin

The molecular target of ______ is ferroportin

39
Q

Iron Transport in Blood

Red cells As _______

Plasma
– Bound to _______
– Carries iron between body locations
– eg between gut, liver, bone marrow, macrophages

A

haemoglobin

Transferrin

40
Q

Iron taken up into cells by transferrin receptors

T/F

41
Q

ENDOCYTOSIS OF TRANSFERRIN

_____ binds to ____ on RBC.
_____ complex localize to ____-coated pits which invaginate to form _____.

A _______ _____eases pH leading to iron release.

______ moves iron across endosomal membrane to cytoplasm.

_________ are recycled to the cell surface for further use.

In RBC most iron is incorporateed into ________ to make _____ (mitochondria).

A

Fe 2+Tf ; TfR1

Fe 2+Tf/TfR1; clathrin; endosomes

proton pump; decreases

DMT1

Apo-Tf& TfRl

protoporphyrin; Heme

42
Q

IRON IN THE ERYTHROBLAST

Iron must be transported to ______ to be incorporated into heme or taken up by _______ within ______.

Within the vesicle, the protein(_____; Nramp2) effects the release of Fe+++ into the cytosol, where it is taken up by mitochondria for heme synthesis.

A

mitochondria

ferritin; siderosomes

DMT-1

43
Q

In the presence of increased iron:

IRP detaches from ______ allowing more ______ to be synthetised.

IRP detaches from ___, _______ synthesis.

A

ferritin mRNA

ferritin

TfR

reducing

44
Q

IRP= __________

IRE= _________

A

Iron Regulatory Proteins (IRP)

Iron Responsive Elements (IRE)

45
Q

IRON SCAVENGING

•Breakdown of red cells in the circulation

Free haemoglobin binds _____ -> taken up by liver

Intravascular haemolysis
Free haem binds ______ -> taken up by liver

Haem passing through ______ is resorbed
Three mechanisms to conserve iron in pathological situations

A

haptoglobins

haemopexin

kidney

46
Q

Historically ________ is the disease we have evolved to avoid.

A

iron deficiency

47
Q

ASSESSMENT OF IRON STATUS

Serum Iron level (___________ level)

TIBC : measurement of _________

% transferrin saturation = (______/_____ x 100)

A

Transferrin bound iron

transferrin

Serum iron/TIBC

48
Q

_______________________ (TIBC)

A

Total iron binding capacity

49
Q

Serum ferritin : Level correlates with body stores _________ assessment in bone marrow

A

Haemosiderin

50
Q

Serum Iron

The serum contains about ___% of body iron

Over ___% of iron in serum is bound to transferrin

51
Q

Serum iron is a routine blood test

T/F

52
Q

Serum iron

______ rythym

Meaning it is (lower or higher?) in the morning

A

Diurnal

Lower

53
Q

Serum iron

Measures all serum iron and those in red cells

T/F

A

F

Measures all serum iron (not in red cells)

54
Q

Serum iron

Of limited use on its own
Useful for interpretation of iron status only if _______– eg iron ______
Commonly combined with ________ to express ____________

A

grossly abnormal

poisoning

serum transferrin

transferrin saturation

55
Q

Serum Iron Measurement

Serum iron is a routine blood test
Low levels:
– Iron deficiency
– Other: Random variation; _____________; pre-______.

High levels:
– Iron Overload
– Other: Random variation, OCP, _______, recent iron ingestion.

A

acute or chronic inflammation; menstrual

pregnancy

56
Q

Total Iron-Binding Capacity

Is the _______________________

A

Amount of Iron that could be bound by transferrin and other minor iron-binding proteins.

57
Q

Total Iron-Binding Capacity

Typically __/3 of iron sites on transferrin are saturated.
Ranges from 250 to 425μg/dl
___eases with serum transferrin

58
Q

transferrin is a (positive or negative?) acute phase protein

59
Q

Transferrin Saturation

Percent of ______________ which are ______
Ranges from _____-____%

Values <__% cannot support erythropoiesis

Combines two factors to improve sensitivity

A

transferrin (TIBC) iron-binding sites

filled with iron; 15-50

15

60
Q

Transferrin Saturation

Iron overload

(High or Low?) iron plus (High or Low?) transferrin

(High or Low?) saturation (________%)

A

High; low

High; 50 – 100

61
Q

Best serum marker of increased body iron is __________

A

Transferrin saturation

62
Q

Transferrin saturation is Used in screening for iron overload

T/F

63
Q

Iron Storage - Ferritin

Iron store in the ____ and nearly all other cells.

Outer shell: ________, consists of 22 protein subunits
________________ core.

A

liver

apoferritin

Iron-phosphate-hydroxide

64
Q

Iron Storage - Ferritin

___% iron by weight, binding up _____ atoms of iron per molecule.
Small fraction found in circulation (contains less than 1% of serum iron).
Stores iron and releases it in a controlled fashion.

65
Q

Ferritin - Measurement

–
High serum levels

Other - Ferritin may be increased in serum by:

Tissue release (_____,______,______)

Acute phase response (____,_____,_____) Interpretation

A

hepatitis, leukaemia, lymphoma

tissue damage, infection, cancer

66
Q

Things you need to know about Laboratory Testing for ferritin

________ most useful test

Low serum ferritin is certain proof that _______

Normal serum ferritin does ____________

Certain conditions raise ferritin for _____________

A

Serum ferritin

patient is iron deficient

not always rule out iron deficiency

reasons unrelated to iron status

67
Q

Bone marrow aspiration

Gives an idea of ___ iron as well as _____ Iron.

_______ stain is used

A

RE; Erythroblast

Pearl’s stain

68
Q

Free unbound iron is toxic

T/F

69
Q

Unbound iron deposited in the heart can cause??

A

Restrictive cardiomyopathy

70
Q

In meat, iron is in the ______ state

In plants, iron is in the _______ state

A

Ferrous

Ferric

71
Q

Only ____ state of iron can be absorbed by the enterocytes

72
Q

______ reduces the fe3+ from plants to Fe2+

A

Duodenum cytochrome B

73
Q

Fe__ is transported by _________ into the enterocytes where it is _______ into ____ and stored as ______

A

2+

Divalent metal transporter(DMT-1)

Oxidized

Fe3+

Ferritin

74
Q

______ oxidizes Fe2+ to Fe3+

A

Hephaestin

75
Q

About ____% of iron is stored as hemoglobin in the marrow

76
Q

3 stages of iron deficiency Anaemia

Stage 1: _____ signs o Anaemia because the body _______

Stage 2: _____ signs of Anaemia and there is ineffective _______

Stage 3: _____ signs of anemia

A

No signs; uses the stored iron

No signs; erythropoesis

There are Signs

77
Q

In severe iron deficiency Anaemia, there is

_____cardia
______ loss
Short _______

A

Tachy
Hair
Attention span

78
Q

Total iron binding capacity

If transporters are exhausted, TIBC is (High or low?)

If transporters are free, TIBC is (High or low?)

79
Q

In iron deficiency Anaemia,

_____eased TIBC
____eased percentage saturation of iron transporters
____eased serum iron
_____eased serum ferritin

A

Incr

Decr

Decr

Decr

80
Q

In Anaemia of chronic inflammation

_____eased TIBC
____eased percentage saturation of iron transporters
____eased serum iron
_____eased serum ferritin

A

Decr
Decr
Decr
Incr

81
Q

In iron deficiency and Anaemia of chronic inflammation combined,

_____eased TIBC
____eased percentage saturation of iron transporters
____eased serum iron
_____eased serum ferritin

A

Decr
Decr
Decr
Decr

82
Q

Iron overload

It can be genetic( defective gene is _____ gene) or acquired

A

HFE( homeostatic iron regulator)

83
Q

Defective HFT gene leads to Down regulation of the production of ______

84
Q

Other types pf primary hemachromatosis

Type 2A- ______ defect
Type 2B-________ defect
Type 3-__________ defect
Type 4-___________ defect

A

Hemojuvelin
Hepcidin
Transferrin receptor
Ferroportin receptor

85
Q

Glucose hinders iron absorption

T/F

A

F

It aids it

86
Q

Iron requirement

Amount that must be absorbed daily for hemoglobin synthesis by :

Infants
Children
Young non pregnant women
Pregnant women
Men
Post menopausal women

87
Q

Iron requirement

Minimal Amount of hemoglobin thgat should Be ingested daily by :

Infants
Children
Young non pregnant women
Pregnant women
Men
Post menopausal women

A

10
5
20
30
10
10

88
Q

Iron is An essential element

T/F

89
Q

Iron content(mg) of ; total body iron(%) of

Hemoglobin
Storage iron
Myoglobin iron
Transport iron

A

2000; 67
1000;27
130; 3.5
3;0.08

90
Q

Function of Ceruloplasmin in iron metabolism

A

Oxidises ferrous to ferric Iron in the plasma

91
Q

LABORATORY MARKERS OF IRON STATUS IN SEVERAL DISEASE STATES

In Malnutrition, everything is ______

In iron overdose , everything is _______

In Hemochromatosis everything is _______

In viral hepatitis , everything is _______

In acute liver disease, everything is _______

In sideroblastic Anaemia, everything is _______

In chronic Anaemia, everything is _______

A

Decreased

Increased, except transferrin that is decreased

Increased, except transferrin that is decreased

Increased

In viral hepatitis , everything is _______

Increased, except transferrin that is decreased

Decreased , expert ferritin that is increased

92
Q

Sideroblastic Anaemia has similar level of iron markers as _______

Viral hepatitis has similar level of iron markers as _______

A

Iron overdose

Acute liver disease

93
Q

Laboratory findings:

Blood film:

____chromic ____cytic Picture.

Occasional ____ cells.

_____shaped ____cytes.

_____ reticulocyte count.

A

Hypo; micro

Target

Pencil; poikilo

Normal

94
Q

Laboratory findings

•Bone marrow iron:
__________cellular.
RBC precursors are ____eased in number.
Iron stain_____tive.

A

Normal to hyper

incr

nega

House Hemat (29 decks)

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