Macrocytic Anaemia

Question 1

what is macrocytic anaemia?

Answer 1

anaemia in which the red cells have a larger than normal size

Question 2

what cell can be used to estimate RBC size?

Answer 2

the mature lymphocytes nucleus

normocytic RBC = same size as this nucleus

Question 3

what red cell precursors have a nucleus?

Answer 3

erythroblasts and normoblasts

reticulocytes do not

Question 4

what is a true macrocytosis?

Answer 4

one in which there is a true increase in the volume of red cells

Question 5

what are the two types of true macrocytosis?

Answer 5

megaloblastic

non-megaloblastic

Question 6

name four causes of non-megaloblastic macrocytosis

Answer 6

alcohol
liver disease
hypothyroidism
marrow failure

Question 7

name three causes of marrow failure that can cause non-megaloblastic macrocytosis

Answer 7

myelodysplasia
myeloma
aplastic anaemia

Question 8

what is a spurious macrocytosis?

Answer 8

red cell volume is normal but MCV is measured as high

Question 9

what is a megaloblast?

Answer 9

an abnormally large nucleated red cell precursor with an immature nucleus

Question 10

what characterises a megaloblastic anaemia?

Answer 10

lack of red cells

maturation of megaloblasts in the marrow - presence of large precursor cells

Question 11

how does a megaloblast become a macrocyte?

Answer 11

once appropriate Hb levels reached in the megaloblast, nucleus is extruded leaving behind a bigger than normal RBC

bevcause cell division has occurred less = less macrocytes = anaemia

Question 12

what are the two main causes of megaloblastic anaemia?

Answer 12

B12 deficiency

folate deficiency

Question 13

what is the treatment of megaloblastic anaemia in pernicious anaemia?

Answer 13

vitamin B12 injections for life

Question 14

what is given for folate deficiency anaemia?

Answer 14

folic acid tablets 5mg daily

Question 15

what are B12 + folate needed for?

Answer 15

DNA synthesis and nuclear maturation

Question 16

how is B12 released from food?

Answer 16

by stomach acid

Question 17

how is B12 protected from the stomach acid?

Answer 17

binds to rapid binder proteins from the saliva or stomach

Question 18

what is secreted by the gastric parietal cells in response to the presence of food in the stomach?

Answer 18

intrinsic factor (IF)

Question 19

what happens to B12 when it reaches the duodenum?

Answer 19

released from binder proteins and binds to IF

Question 20

where is B12 bound and in what form?

Answer 20

the distal small bowel

bound to IF

Question 21

what does B12 bind to in circulation?

Answer 21

transcobalamin (TC) receptors

Question 22

name two sources of B12 in the diet

Answer 22

meat

eggs

Question 23

what gastric conditions can cause B12 deficiency?

Answer 23

atrophic gastritis

pernicious anaemia

Question 24

what medications can lead to B12 deficiency?

Answer 24

PPIs

H2 receptor antagonists

Question 25

what small bowel conditions can result in B12 defiiency?

Answer 25

bacterial overgrowth coeliac crohn's

Question 26

what surgeries can increase risk of B12 deficiency?

Answer 26

gastrectomy | resection

Question 27

what are dietary folates converted to for absorption?

Answer 27

monoglutamate

Question 28

where is monoglutamate absorbed?

Answer 28

jejunum

Question 29

name some possible causes of folate deficiency

Answer 29

inadequate intake malabsorption excess utilisation drugs

Question 30

which has higher body stores - folate or B12?

Answer 30

B12 (much more)

Question 31

name four states that can lead to excess folate utilisation

Answer 31

haemolysis exfoliating dermatitis pregnancy malignancy

Question 32

what group of drugs can cause folate deficiency?

Answer 32

anti-convulsants

Question 33

what foods are a source fo folate?

Answer 33

leafy veg liver fortified cereals

Question 34

how long to body stores of B12 and folate last?

Answer 34

``` B12 = 2-4 years folate = 4 months ```

Question 35

which is higher - daily requirement of folate or B12?

Answer 35

folate (200ug/day) B12 is 1.5ug/day

Question 36

what serious way can B12 deficiency present?

Answer 36

neurological problems - subacute combined degeneration of the cord

Question 37

what does blood film in B12/folate deficiency anaemia show?

Answer 37

macrocytes | hyper-segmented neutrophils

Question 38

what investigations are done for B12/folate deficiency?

Answer 38

measure B12 + folate check for auto-antibodies to rule out PA trial of therapy

Question 39

in what states can low B12 not indicate B12 deficiency?

Answer 39

pregnancy | on the COCP

Question 40

what auto-antibodies are present in pernicious anaemia (PA)?

Answer 40

anti gastric parietal cell (GPC) | anti IF

Question 41

what is pernicious anaemia?

Answer 41

an autoimmune condition resulting in destruction of gastric parietal cells = IF deficiency

Question 42

what are some risk factors for pernicious anaemia?

Answer 42

atrophic gastritis | personal or family history of other autoimmune disorders

Question 43

what causes non-megaloblastic macrocytosis?

Answer 43

red cell membrane changes

Question 44

what are two possible causes of a spurious macrocytosis?

Answer 44

reticulocytosis - bigger than RBCs | abnormal clumping of cells due to cold agglutinins