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Haematology > Iron* > Flashcards

Iron* Flashcards

1
Q

what is iron used for

what is it present in

A

oxygen transport
electrons transport

Hb, myoglobin, enzymes

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2
Q

adaptive requirements for iron why and what

A

chemical reactivity: oxidative stress

safe transport, safe storage, regulation of iron absorption

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3
Q

where does iron sit in Hb

A

Fe2+ sits in the porphyria ring

this is where most of the body iron resides i.e. in Hb

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4
Q

what are the three compartments for iron stair assessment

A

functional iron - Hb conc

transport iron/iron supply to tissues - % saturation of transferrin w iron

storage iron - serum ferrari, tissue biopsy [bone marrow for iron defic and liver for overload]

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5
Q

what is transferrin

A

protein with two binding sites for iron atoms

transports iron from donor tissues (macrophages, intestinal cells and hepatocytes) to tissues expressing transferrin receptors (especially erythroid marrow)

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6
Q

transferrin sat measures what

A

iron supply

approx 20-50%

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7
Q

holotransferrin

apotransferrin

A

iron bound to transferrin

unbound transferrin

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8
Q

what happens to transferrin sat in iron overload

in iron defic

A

increases

goes down

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9
Q

what is ferritin

A

large intracellular protein
spherical rpotetin
stores up to 4000 ferric ions
stores iron in Fe3+ form

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10
Q

measure of ferritin is what

A

indirect measure of storage iron

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11
Q

what are other causes of increase in serum ferratin

A

its an acute phase protein so infection, malig etc

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12
Q

ferritin in defic
overload
inflam/sepsis/malig/liver injury

A

down
v high
high

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13
Q

how is iron absorption regulated

A

intraluminal factors - solubuility of inorganic iron, haem iron easier to absorb, reduction of ferric to ferrous

mucosal factors - expression of iron transports- DMT1 at mucous surface, ferroportin at serial surface

systemic factors (hepcidin) - major neg regulator of iron uptake, produced in liver in response to iron load and inflam, down regulates ferroportin

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14
Q

DMT 1

A

transports iron into duodenal enterocyte

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15
Q

Ferroportin

A

faciloctaes iron export from the enterocyte

passed onto transferrin for transport elsewhere

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16
Q

Hepcidin

A

down regulates ferroportin

17
Q

disorders of iron metab

A

iron dfic
iron malutilisation
iron overloaf

18
Q

iron defic

A

iron defic erythropoiesis - low MCV
microcytic anaemia
skin, koilonychia, angular stomatitis

19
Q

hypo chromic microcytic anaemias =

A

deficient haemoglobin synthesis

20
Q

hypochromic microcytic anaemias haem defic

A

lack of iron for eryhtro because of iron defic or anaemia of chronic disease
congenital sidroblastic anaemia

21
Q

hypochromic microcytic anaemias globin defic

A

thalassaemias

22
Q

what can iron defic be a combination of

A

anaemia (decreased Hb iron) and reduced storage iron (low serum ferritin)

23
Q

causes of iron defic

A

diet
bleeding
malabsorption

24
Q

causes of chronic blood loss

A

menorrhagia
GI - tumours, ulcers, NSAIDs, parasitic
haematuria

25
Q

occult blood loss how much

why neg iron balance

A

GI blood loss of 8-10ml (4-5mg)/day can occur without symptoms or signs

max dietary iron absortpn is 4-5mg/day

26
Q

iron malutilisation

A

increased transcription of ferritin mRNA by inflam cytokines to ferritin synthesis increased

increased hepcidin blocks ferritin mediated release of iron

leads o impaired iron supply to marrow erythroblasts and eventually hypochomic red cells

27
Q

primary iron overload

A

long term iron absorption with parenchymal rather than macrophage iron loading

28
Q

heridiatyr haemochormatosis features

when present

A 
weakness/fatigue
joint pains
impotence
arthritis 
cirrhosis
DM
cardiomyopathy
stays asymp till organ damage

middle age or later
iron >5mg

29
Q

molecular dx pf haemochrom

A

mutations in HFE gene

mutations in other iron regulatory proteins

30
Q

diagnosis of haemochrom phenotype

A

risk of iron landing: transferrin sat >50%

iron load: ferritin >300 in men or >200 in pre menopausal women

liver biopsy - if uncertain about iron loading or assess tissue damage

31
Q

treatment of heriditary haem

A

phlebotomy weekly 400-500ml, 200-250mg iron

aim to exhaust iron stores and keep ferritin <50

32
Q

family screening for HH

A

siblings 1/4 risk

HFE genotype and iron status (ferritin and transferritin)

33
Q

secondary iron overload

A

repeated red cell transfusions
excessive iron absorption related to over active eryhtro

thalassaemia
sideroblastic anaemia

red cell aplasia
myelodysplasia

34
Q

blood transfusions

A

each unit has 200-250mg or iron

35
Q

treatment of secondary iron overload

A

venesection not an option in already anaemic patients

desferrioxamine sc or IC
deferiprone or deferairox PO

Haematology (26 decks)

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