Microcytic anaemia

Question 1

what is anaemia

Answer 1

reduced total red cell mass

Question 2

how is total red cell mass measured

Answer 2

Hb used as a surrogate marker (spectrophotometric method)

as it haematocrit (ratio or percentage of whole blood that is red cells)

Question 3

what are the Hb levels that suggest anaemia

Answer 3

adult males <130

adult females <120

Question 4

when might Hb/hct not be a good marker of anaemia

Answer 4

when patient not in a steady state- e.g. rapid blood volume loss, plasma expansion (haemodilution)

Question 5

what is the reaction to anaemia

Answer 5

reticulocytosis (usually takes a few days- in massive haemorrhage can produce some quicker)

Question 6

what are reticulocytes

Answer 6

red cells that have just left the bone marrow
larger than mature cells, still have RNA remnants - stain purple as a result
appear polychromatic on blood film

Question 7

what does reticulocyte count assess

Answer 7

marrow response

Question 8

what does blood film assess

Answer 8

cellular morphology

Question 9

what are the two pathophysiological types of anaemia

Answer 9

decreased production- low reticulocyte count, not producing cells

increased loss or destruction of red cells- high reticulocyte count, lots of immature cells trying to replace loss

Question 10

what can cause decreased rbc production

Answer 10

hypoproliferative- reduced amount of erythropoiesis
maturity abnormality- erythropoiesis present but ineffective: cytoplasmic defects (impaired haemoglobulinisation, nuclear defects causing impaired cell division)

Question 11

what can cause increased loss of destruction of rbcs

Answer 11

bleeding

haemolysis (premature red cell degeneration)

Question 12

how is anaemia classified in practise

Answer 12

using cell size and Hb content

Question 13

what does a low MCV mean

Answer 13

microcytic

(in the context of low reticulocyte count) =cytoplasmic defect resulting in problems with haemoglobinisation

Question 14

what does a high MCV mean

Answer 14

macrocytic

(in the context of low reticulocyte count) = nuclear defect causing impaired cell division and maturation

Question 15

what does anaemia with a normal MCV count mean

Answer 15

hypoproliferative problem

Question 16

where does haemoglobin synthesis occur

Answer 16

in the cytoplasm - defects in this leads to small cells= microcytic

Question 17

what is needed to make Hb

Answer 17

globins

haem (porphyrin ring, iron (Fe2+)

Question 18

what colour are cells with deficiency in Hb

Answer 18

hypochromic

Question 19

what type of anaemia results from inability to make Hb

Answer 19

microcytic

Question 20

what can cause hypochromic microcytic anaemias

Answer 20

deficient haemoglobin synthesis (cytoplasmic defect):
haem deficiency
-IRON DEFICIENCY
-anaemia of chronic disease (these usually normocytic)

porphyrin ring synthesis
-lead poisoning

globin deficiency
-THALASSAEMIA (problem of globin chain synthesis)

Question 21

what states can iron exist in

Answer 21

Fe2+ or Fe3+

Question 22

what is the role of iron

Answer 22

oxygen transport as Hb or myoglobin

electron transport in ATP production in mitochondria

Question 23

describe the composition of haemoglobin

Answer 23

4 globin protein subunits (2 alpha 2 beta) each contains a single haem molecule
haem molecule contains single Fe2+ ion and can bind with a single O2 molecule

Question 24

when fully saturated how much O2 will bind to 1g of Hb

Answer 24

1.34ml

Question 25

how is iron stored in the body

Answer 25

most is in haemoglobin | rest in liver and macrophage stores as the molecule ferritin (mainly in liver)

Question 26

what is circulating iron bound to

Answer 26

transferrin (this feeds it tobone marrow macrophages that then feed it to red cell precursors)

Question 27

what are the tests that assess iron status

Answer 27

function iron- Hb transported iron- serum iron, transferring, transferring saturation stored iron- serum ferritin

Question 28

what is transferrin

Answer 28

protein with two binding sites for iron atoms that transports iron from donor tissues (macrophages, intestinal cells, hepatocytes) to tissues expressing transferrin receptors (erythroid marrow)

Question 29

what can alter the % saturation of transferrin with iron

Answer 29

reduced in iron deficiency reduced in anaemia of chronic disease increased in genetic haemachromatosis

Question 30

what is ferritin

Answer 30

large intracellular protein that stores ferric ions

Question 31

why is only a small amount of ferritin present in serum

Answer 31

as intracellular

Question 32

what is serum ferritin a measure of

Answer 32

indirect measure of storage iron | low ferritin means iron deficiency

Question 33

what does low ferritin mean

Answer 33

iron deficiency

Question 34

what can cause increased ferritin

Answer 34

in the acute phase of an infection

Question 35

what confirms irons deficiency

Answer 35

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

Question 36

what can cause iron deficiency

Answer 36

diet: relative deficiency (women of childbearing age), absolute deficiency (veggies/vegans) (diet unusual to cause deficiency in men) blood loss: usually GI, menorrhagia malabsorption: coeliac disease, achlorhydia (e.g. people on PPIs, need acid to absorb iron)

Question 37

where in GI tract do you absorb iron

Answer 37

proximal small bowel (e.g. affected in coeliac)

Question 38

what are potential causes of chronic blood loss

Answer 38

menorrhagia GI- tumours, ulcers, NSAIDs haematuria

Question 39

what is the average daily intake of iron

Answer 39

1mg/day | in menorrhagia loose >30mg/ month

Question 40

what are the consquences of low iron

Answer 40

exhaust iron stores (ferritin will go down) iron deficient erythropoiesis (falling red cell MCV) epithelial changes: skin, koilonychia

Question 41

what is occult blood loss

Answer 41

when small volume of GI blood loss can occur without any symptoms/ signs this can outstrip the maximum dietary iron absorption = anaemia

Question 42

is iron deficiency anaemia a diagnosis or a symptom

Answer 42

symptom- need to investigate and find underlying cause

Question 43

what is the risk or iron replacement therapy

Answer 43

relieve symptoms without treating underlying problems