microcytic anaemia

Question 1

what are microcytic anaemias classified by visually

Answer 1

erythrocytes smaller than normal
paler than normal ( hypochromic)

Question 2

what are the two causes of microcytic anaemia

Answer 2

• reduced haem synthesis
• reduced globin chain synthesis

Question 3

what are the four causes of reduced haem synthesis

Answer 3

• iron deficiency
• lead poisoning
• anaemia of chronic disease
• sideroblastic anaemia

Question 4

what is sideroblastic anaemia

Answer 4

inherited defect in haem synthesis

Question 5

what are the two causes of reduced globin chain synthesis

Answer 5

• a thalassemia
• b thalassemia

Question 6

what does TAILS stand for

Answer 6

T- thalassemia
A- anaemia of chronic
I- iron deficiency
L- lead poisoning
S- sideroblastic anaemia

Question 7

what is iron require for

Answer 7

• oxygen carriers in Hb and myoglobin
• co-factors in enzymes:
  cytochromes
  krebs
  cytochrome P450
  catalase

Question 7

why is free iron dangerous

Answer 7

free iron is toxic to cells but body has no mechanism for excreting iron

Question 8

what is ferrous iron

Answer 8

Fe2+

Question 9

what is ferric iron

Answer 9

Fe3+

Question 10

what is the difference between ferric and ferrous iron

Answer 10

Fe2+ is reduced form while Fe3+ is oxidised form

Question 11

what does dietary iron consist of

Answer 11

haem iron Fe2+
non-haem (mix of 2+ and 3+)

Question 12

how much iron do we need a day in our diet

Answer 12

10-15 mg/day

Question 13

where is iron absorbed

Answer 13

duodenum
jejunum

Question 14

what is chyme

Answer 14

food passing through intestine

Question 15

what form of iron is only absorbed

Answer 15

only ferrous iron (Fe2+) can be absorbed so ferric iron must be reduced to ferrous iron to be absorbed

Question 16

what are the ways iron is absorbed from the diet into enterocytes

Answer 16

• haem readily absorbed converted to Fe2+ by haem oxygenase
• Fe2+ is transported through DMT1 (divalent metal transporter) into cells
• Fe3+ converted to Fe2+ by reductase using vitamin C

Question 17

where is iron stored

Answer 17

ferritin protein

Question 18

what transport ferrous iron into blood

Answer 18

ferroportin

Question 19

what is hephaestin

Answer 19

converts Fe2+ to Fe3+ in blood to be transported around the body

Question 20

what is hepcidin and where is it made

Answer 20

inhibits ferrroportin so less iron absorbed into blood

liver

Question 21

what is transferrin

Answer 21

transports Fe3+ around the body

Question 22

what factors negatively influence iron absorption

Answer 22

• tannins in tea
• phytates (pulses, chapattis)
• fibre
• antacids (gavison)

Question 23

what factors positively influence iron absorption

Answer 23

vitamin C and citrate

Question 24

how do the negative factors reduce absorption of iron

Answer 24

bind to non - haem iron in the intestine

Question 25

how do positive factors increase iron absorption

Answer 25

- prevent formation of insoluble iron compounds - vit C helps reduce ferric to ferrous iron

Question 26

in what form is iron transported around the body

Answer 26

Fe3+

Question 27

where is functional iron found in the body

Answer 27

- haemoglobin - myoglobin - enzymes - transported iron

Question 28

what is the soluble form of stored iron

Answer 28

ferritin

Question 29

what is the insoluble store of iron

Answer 29

haemosiderin

Question 30

where is haemosiderein accumulated.

Answer 30

macrophages, liver, spleen and marrow

Question 31

what is haemosiderin

Answer 31

aggregates of clumped ferritin particles, denatured proteins and lipid

Question 32

how is iron uptaken by cells

Answer 32

- transferrin with Fe3+ binds to transferrin receptor and enters cytosol by receptor mediated endocytosis - Fe3+ in endosome released by acidic microenvironment and reduced to Fe2+ - Fe2+ transported to cytosol by DMT1 - Fe2+ stored in ferritin, exported by ferroportin or taken up by mitochondria for use in cytochrome enzymes

Question 33

where is most of the total daily iron requirement from

Answer 33

more than 80% of iron requirement met from recycling damaged or old RBC

Question 34

how is iron recycled

Answer 34

old RBC engulfed by macrophages bby splenic cells and kupffer ells macrophages catabolise haem released from RBC iron exported to blood (transferrin) or returned to storage pool as ferritin in macrophage

Question 35

how is iron absorption regulated

Answer 35

- depend on dietary factors, body iron stores and erythropoiesis - sensed by enterocytes - regulation or transporters, receptors, hepcidin and cytokines

Question 36

what regulates hepcidin synthesis

Answer 36

- increased by iron overload - decreased by high erythropoietic activity

Question 37

how does hepcidin regulate iron absorption

Answer 37

induces internalisation and degradation of ferroportin

Question 38

how does anaemia of chronic disease cause anaemia

Answer 38

- inflammatory condition releases cytokines - increases production of hepcidin - inhibits ferroportin -