Week Review

Question 1

causes of macrocytosis?

Answer 1

alcohol (mild)
liver disease
hypothyroid
physiological (pregnancy, neonatal, reticulocytosis)
nuclear maturation defect (megaloblastic - B12 or folate deficiency, myelodysplasia - stem cell mutation)

Question 2

is macrocytosis always associated with anaemia?

Answer 2

no

Question 3

what is pernicious anaemia associated with?

Answer 3

autoimmune disorders eg hypothyroid

Question 4

what can influence serum folate?

Answer 4

diet

Question 5

approach to diagnosing macrocytosis?

Answer 5

by severity
whether anaemia is present
if neutrophils or platelets are low
blood film

Question 6

MCV >120 indicates what?

Answer 6

B12 or folate deficiency

Question 7

macrocytosis with anaemia indicates what?

Answer 7

megaloblastic or myelodysplasia

Question 8

low platelets/neutrophils indicates what in macrocytosis?

Answer 8

myelodysplasia or megaloblastic

Question 9

possible features on blood film in macrocytosis?

Answer 9

hypersegmented neutrophils and oval macrocytes (megaloblastic)
uniform microcytosis (probably alcohol)
dysplastic neutrophils (myelodysplasia)
polychromasia (reticulocytosis)
agglutinates (artefact with cold agglutinins)

Question 10

how can iron status be measured?

Answer 10

3 compartments

• functional iron (Hb conc)
• storage iron (serum ferritin, bone marrow biopsy with perls stain)
• transport iron (serum transferrin % saturation with iron)

Question 11

which compartment of iron is used up first?

Answer 11

storage iron exhausted first before transport iron, only then is RBC production affected

Question 12

causes of iron deficiency

Answer 12

diet
increased physiological requirement
blood loss
malabsorption (jejunum, need gastric acid)

Question 13

how is iron deficiency investigated?

Answer 13

history
blood loss (FOB testing of little value in iron deficiency)
GI tract investigations (upper GI endoscopy, barium enema or colonoscopy)

Question 14

normal initial reticulocyte response?

Answer 14

reticulocytosis 6-12 hrs after bleed as immature retics released
proliferative response to increased erythropoietin production 1-2 days after acute bleed, peaking at day 8-10

Question 15

what does reticulocyte response indicate?

Answer 15

normal marrow response

normal iron as only possible if iron supply is adequate

Question 16

normal marrow response to marked anaemia?

Answer 16

6-8X increase in absolute reticulocyte count
3-4X increase in amount of erythropoiesis
earlier release of reticulocytes into blood

Question 17

signs of shock?

Answer 17

tachycardia
hypotension (can be postural in young people)
tachypnoea
peripheral vasoconstriction (pallor, delayed capillary refill)
oliguria

Question 18

causes of shock?

Answer 18

hypovolaemic (acute blood loss)
cardiogenic (pump failure)
neurogenic (lack of sympathetic tone - can happen after sudden neck injury)
vasogenic (anaphylactic or septic)

Question 19

how is Hb affected in hypovolaemic shock?

Answer 19

unchanged until redistribution of body water

Question 20

how is shock treated?

Answer 20

synthetic colloids as immediate fluid of choice

Question 21

how can oxygen delivery be restored in shock?

Answer 21

Hb
supplemental oxygen
optimise cardiopulmonary dynamics (fluids and pharmacological interventions)

Question 22

what are the 3 elements of cross matching?

Answer 22

ABO and RhD antigen grouping
screen for alloantibodies in patient (identify alloantibodies in the patient to antigens which might be on the donor RBCs and if found, check that donor blood doesn’t have that antigen)
mix donor cells and recipient plasma to double check
confirm historical records for electronic cross match

Question 23

how available is crossmatched blood?

Answer 23

not in a hurry
ABO group is quickest test
alloantibody takes longer (difficult to get ag -ve blood etc)

Question 24

what types of blood are available quickly?

Answer 24

O RhD -ve
ABO type specific
fully crossmatched
electronic crossmatched (if historical group and -ve alloantibody screen)

Question 25

what can incompatible ABO transfusion cause?

Answer 25

immediate transfusion reaction

- DIC and death due to presence of preformed IgM antibodies (anti-A/B)

Question 26

how does a delayed transfusion reaction occur?

Answer 26

IgG alloantibody to RBC antigen
acquired following previous transfusion or pregnancy
low level 2ndary response 10 days later

Question 27

complications of transfusion?

Answer 27

infective
overload (fluid overload/TACO, iron overload)
immune complications (febrile non-haemolytic reactions, urticarial reactions, taGVHD, PTP, IgA deficiency, TRALI)