Iron*

Question 1

what is iron used for

what is it present in

Answer 1

oxygen transport
electrons transport

Hb, myoglobin, enzymes

Question 2

adaptive requirements for iron why and what

Answer 2

chemical reactivity: oxidative stress

safe transport, safe storage, regulation of iron absorption

Question 3

where does iron sit in Hb

Answer 3

Fe2+ sits in the porphyria ring

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

Question 4

what are the three compartments for iron stair assessment

Answer 4

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]

Question 5

what is transferrin

Answer 5

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)

Question 6

transferrin sat measures what

Answer 6

iron supply

approx 20-50%

Question 7

holotransferrin

apotransferrin

Answer 7

iron bound to transferrin

unbound transferrin

Question 8

what happens to transferrin sat in iron overload

in iron defic

Answer 8

increases

goes down

Question 9

what is ferritin

Answer 9

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

Question 10

measure of ferritin is what

Answer 10

indirect measure of storage iron

Question 11

what are other causes of increase in serum ferratin

Answer 11

its an acute phase protein so infection, malig etc

Question 12

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

Answer 12

down
v high
high

Question 13

how is iron absorption regulated

Answer 13

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

Question 14

DMT 1

Answer 14

transports iron into duodenal enterocyte

Question 15

Ferroportin

Answer 15

faciloctaes iron export from the enterocyte

passed onto transferrin for transport elsewhere

Question 16

Hepcidin

Answer 16

down regulates ferroportin

Question 17

disorders of iron metab

Answer 17

iron dfic
iron malutilisation
iron overloaf

Question 18

iron defic

Answer 18

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

Question 19

hypo chromic microcytic anaemias =

Answer 19

deficient haemoglobin synthesis

Question 20

hypochromic microcytic anaemias haem defic

Answer 20

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

Question 21

hypochromic microcytic anaemias globin defic

Answer 21

thalassaemias

Question 22

what can iron defic be a combination of

Answer 22

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

Question 23

causes of iron defic

Answer 23

diet
bleeding
malabsorption

Question 24

causes of chronic blood loss

Answer 24

menorrhagia
GI - tumours, ulcers, NSAIDs, parasitic
haematuria

Question 25

occult blood loss how much | why neg iron balance

Answer 25

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

Question 26

iron malutilisation

Answer 26

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

Question 27

primary iron overload

Answer 27

long term iron absorption with parenchymal rather than macrophage iron loading

Question 28

heridiatyr haemochormatosis features when present

Answer 28

``` weakness/fatigue joint pains impotence arthritis cirrhosis DM cardiomyopathy stays asymp till organ damage ``` middle age or later iron >5mg

Question 29

molecular dx pf haemochrom

Answer 29

mutations in HFE gene | mutations in other iron regulatory proteins

Question 30

diagnosis of haemochrom phenotype

Answer 30

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

Question 31

treatment of heriditary haem

Answer 31

phlebotomy weekly 400-500ml, 200-250mg iron aim to exhaust iron stores and keep ferritin <50

Question 32

family screening for HH

Answer 32

siblings 1/4 risk | HFE genotype and iron status (ferritin and transferritin)

Question 33

secondary iron overload

Answer 33

repeated red cell transfusions excessive iron absorption related to over active eryhtro thalassaemia sideroblastic anaemia red cell aplasia myelodysplasia

Question 34

blood transfusions

Answer 34

each unit has 200-250mg or iron

Question 35

treatment of secondary iron overload

Answer 35

venesection not an option in already anaemic patients desferrioxamine sc or IC deferiprone or deferairox PO