haemoglobin

Question 1

where is most iron present

Answer 1

haemoglobin (otherwise present in myoglobin, catalase, cytochrome P450, succinate dehydrogenase, ribonucleotide reductase, cyclo-oxygenase, cytochrome a, b, c

Question 2

function of iron in haemoglobin

Answer 2

bind to oxygen

Question 3

what can low iron levels cause

Answer 3

low Hb, causing anaemia

Question 4

what part of haemoglobin is iron present in, and how many in a molecule of haemoglobin

Answer 4

haem group, of which there are 4

Question 5

what is each haem group associated with

Answer 5

single globin chain

Question 6

lifespan of red cells

Answer 6

120 days

Question 7

how is high amount of iron provided to re-make huge numbers of red cells

Answer 7

recycled and some from diet

Question 8

why is some iron required from diet

Answer 8

desquamated cells of skin and gut, bleeding (menstruation or pathological, hence women need 2mg/day and men only need 1mg/day)

Question 9

foods containing iron

Answer 9

meat and fish (haem iron so easy to absorb), vegetables, whole grain cereal, chocolate

Question 10

what iron cannot be absorbed

Answer 10

Fe3+ ferric iron (most iron eaten); only Fe2+ ferrous iron can be absorbed

Question 11

what helps and hinders iron absorption

Answer 11

orange juice helps, tea hinders

Question 12

3 factors which affect absorption

Answer 12

diet, intestine, systemic

Question 13

how does diet affect absorption

Answer 13

increase in haem iron, ferrous iron

Question 14

how does intestine affect absorption

Answer 14

acid (duodenum), ligand (meat)

Question 15

how does systemic affect absorption

Answer 15

iron deficiency (absorb more iron than normal), anaemia/hypoxia, pregnancy

Question 16

process of absorption in duodenum (binding proteins)

Answer 16

iron in diet -> Fe2+ absorbed into duodenual cell by binding to ferritin IC (iron storage protein) -> iron in plasma binds to transferrin

Question 17

how does gut cell alter iron absorption (e.g. if high iron)

Answer 17

must go through ferroportin to go through basal membrane of gut cell into blood: if high iron -> high hepcidin -> this causes low ferroportin as destroys it -> low absorption

Question 18

3 things about transferrin that are measured

Answer 18

transferrin, total iron binding capacity (TIBC - almost same as transferrin), transferrin saturation (20-50%)

Question 19

effect of anaemia on erythropoietin and outcome

Answer 19

anaemia -> tissue hypoxia -> increase in erythropoietin -> red cell precursors (survive, grow, differentiate)

Question 20

what is anaemia of chronic disease

Answer 20

anaemia in patients who are unwell, who aren’t bleeding, have marrow infiltrated or are iron/B12 or folate deficient (exclude these and left with no obvious cause except patient is ill)

Question 21

3 laboratory signs of being ill with anaemia of chronic disease

Answer 21

C-reactive protein (increases during inflammation or infection), erythrocyte sedimentation rate (increases non-specifically when unwell), increases in some acute phase response proteins

Question 22

in anaemia of chronic disease, what acute phase response proteins increase

Answer 22

ferritin, FVIII, fibrinogen, immunoglobulins

Question 23

4 associated conditions (causes) of anaemia of chronic disease

Answer 23

chronic infections e.g. TB/HIV, chronic inflammation e.g. RhA - rheumatoid arthritis/SLE, malignancy, miscellaenous e.g. cardiac failure

Question 24

what do cytokines do in anaemia of chronic disease

Answer 24

block in iron utilisation by preventing usual flow of iron from duodenum to red cells (iron is present but not in red cells)

Question 25

3 other things cytokines do in anaemia of chronic disease besides prevent usual flow of iron

Answer 25

stop erythropoietin increasing, increase production of ferritin, increase death of red cells

Question 26

3 consequences of cytokine actions in anaemia of chronic disease

Answer 26

make less red cells, more red cells die, less availability of iron (stuck in cells/ferritin)

Question 27

2 classes of cytokines involved in anaemia of chronic disease

Answer 27

TNF alpha, interleukins

Question 28

4 causes of iron deficiency

Answer 28

bleeding e.g. menstrual/GI, increased use e.g. growth/pregnancy, dietary deficiency e.g. vegetarian, malabsorption e.g. coeliac

Question 29

when would you conduct a full GI investigation in iron deficiency

Answer 29

good diet with no coeliac antibodies and: male, women over 40, post menopausal women, or women with scanty menstrual loss

Question 30

3 GI investigations in iron deficiency

Answer 30

upper GI endoscopy (oesophagus, stomach, duodenum), take duodenal biopsy, colonoscopy

Question 31

GI investigation if find nothing after previous 3 in iron deficiency

Answer 31

small bowel meal and follow through

Question 32

3 other investigations for iron deficiency

Answer 32

if mensturating women <40 (heavy periods or multiple pregnancies and no GI symptoms) do nothing; urinary blood loss (chronic blood loss e.g. renal cancer); antibodies for coeliac disease

Question 33

5 laboratory paramteres for iron deficiency

Answer 33

MCV, serum iron, ferritin, transferrin (= total iron binding capacity, TIBC), transferrin saturation

Question 34

3 causes of low MCV

Answer 34

iron deficiency, thalassaemia trait, anaemia of chronic disease (low or normal)

Question 35

what can be excluded if low serum iron

Answer 35

thalassaemia trait (normal serum iron)

Question 36

how to confirm thalassaemia trait

Answer 36

haemoglobin electrophoresis to confirm additional type of haemoglobin present

Question 37

when is ferritin low

Answer 37

iron deficiency

Question 38

when is ferritin high (as acute phase protein, or can be normal)

Answer 38

anaemia of chronic disease

Question 39

when is ferritin not perfect

Answer 39

if iron deficient but with underlying chronic disease e.g. rheumatoid arthritis plus bleeding ulcer (ferritin can be normal despite being iron deficient as increased as part of acute phase response)

Question 40

lab clues that ferritin is not ideal

Answer 40

raised C-reactive protein and erythrocyte sedimentation rate

Question 41

transferrin levels in iron deficiency

Answer 41

increased

Question 42

transferrin levels in anaemia of chronic disease

Answer 42

normal/low

Question 43

transferrin saturation in iron deficiency

Answer 43

low saturation (as more transferrin)

Question 44

transferrin saturation in anaemia of chronic disease

Answer 44

normal

Question 45

4 further main investigations if iron deficient

Answer 45

endoscopy and colonscopy, duodenal biopsy, anti-helicobacter antibodies, anti-coeliac antibodies

Question 46

3 other investigations if iron deficient

Answer 46

abdominal ultrasound to look at kidneys, dipstick urine, pelvic ultrasound to exclude fibroids

Question 47

classic iron deficiency: Hb, MCV, serum iron, ferritin, transferrin, transferrin saturation

Answer 47

Hb low, MCV low, serum iron low, ferritin low, transferrin high, transferrin saturation low

Question 48

anaemia of chronic disease: Hb, MCV, serum iron, ferritin, transferrin, transferrin saturation

Answer 48

Hb low, MCV low or normal, serum iron low, ferritin high or normal, transferrin normal/low, transferrin saturation normal

Question 49

thalassaemia trait: Hb, MCV, serum iron, ferritin, transferrin, transferrin saturation

Answer 49

Hb low, MCV low, serum iron normal, ferritin normal, transferrin normal, transferrin saturation normal

Question 50

iron deficient with underlying chronic disease (e.g. RhA with bleeding ulcer): Hb, MCV, serum iron, ferritin, transferrin saturation

Answer 50

Hb low, MCV low, serum iron low, ferritin normal, transferrin saturation low

Question 51

additional tests when invesitgating iron deficiency

Answer 51

blood film (small, pale, strange shapes including pencil cells), stain bone marrow for iron

Question 52

what to do if uncertain diagnosis with low iron

Answer 52

give iron and see if anaemia improves

Question 53

what does low ferritin in men of any age indicate, and what must be done

Answer 53

iron deficiency, must have upper and lower GI endoscopies to look for source of bleeding