PLT

Question 1

Why can splenectomy cause high PLT? (1)

Answer 1

Spleen normally sequester PLT, removal of spleen causes less PLT being removed, leading to high PLT

Question 2

Why can aspirin prevent PLT aggregation? (2)

Answer 2

Inhibit COX, prevent formation of TXA2

Question 3

Name 2 main players in PLT adhesion (2)

Answer 3

vWF & GPIb

Question 4

Why in vWF disease, APTT will increase? (1) Is PLT decreasing in vWF disease? (1)

Answer 4

Factor 8 is vWF dependent & involved in APTT cascade
PLT usually normal in patient with vWF disease

Question 5

Give 4 distinctive results to diagnose BSS (3) What exactly is BSS? (1) How about GT? (1)

Answer 5

Low PLT
Giant PLT
Normal ADP & Collegen & Epi, Abnormal Ristocetin (same for vWFD, reverse for GT)
CD42b- by flow cytometry (CD41/61- for GT)

BSS is GPIb (vWFR) deficiency
GT is GPIIb/IIIa (FIBR) deficiency

vwf acts on 1b (assisted by ristocetin), collagen acts on 1a, fibrinogen acts on 2b3a (assisted by ADP through P2Y12), that’s why when only ristocetin is added, the plt aggregation can’t happens due to defective 1b in case of bss

Question 6

Why do some patients develop ITP? (1)

Answer 6

Viral infection

Question 7

ADAMTS13 result is not available yet, how can you tell if the patient is having TTP or DIC? (1)

Answer 7

PT/APTT is abnormal in DIC but normal in TTP

Question 8

HDFN has Antibody targeting RBC, is there a condition targeting PLT? (1)

Answer 8

anti-HPA1a
Also occur after transfusion

Question 9

State 5 signs of TTP & HUS (5) Which sign is more common in TTP, HUS respectively? (2)

Answer 9

FATRN (Fever, Anaemia, Thrombocytopenia, Renal failure, Neurological symptoms)
Neurological symptoms in TTP
Renal failure in HUS

Question 10

What are Storage pool deficiencies? (1)

Answer 10

PLT granule deficiency causing decreased release of ADP, ATP, calcium, and serotonin
ATP release can be measured by Lumi-aggregation

Question 11

How can TTP be acquired? (1)

Answer 11

Anti-ADAMTS13

Question 12

What is Hereditary hemorrhagic telangiectasia (HHT)? (2)

Answer 12

AD, Abnormal blood vessels leading to bleeding
Adolescence who have Nose bleed everyday
Can progress to stroke & HF

Question 13

TXA2 stimulates PLT aggregation, what inhibits PLT aggregation? (1)

Answer 13

Prostacyclin from endothelial cell

Question 14

You see agranular PLT in FR, what would you suspect? (1)

Answer 14

Gray’s syndrome (Alpha granule deficiency)

Question 15

Instead of taking aspirin, the patient was prescribed clopidogrel/prasugrel as antiPLT, how to monitor its effect? (1)

Answer 15

irreversibly binding to P2Y12 (ADP R)
whole blood test using ADP as agonist
Report as % P2Y12 inhibition

Question 16

The main use of platelet aggregometer, Lumi-aggregometer, VerifyNow, PFA-100 (4)

Answer 16

platelet aggregometer: BSS vs GT
Lumi-aggregometer: PLT granule deficiency
VerifyNow: monitor P2Y12 inhibitor like clopidogrel
PFA-100: Screening, collagen/EPI&raquo_space; collagen/ADP (If EPI+ADP- suspect aspirin)

Question 17

Which agonist gives a monophasic response? (1)

Answer 17

Collagen

Question 18

We give low dose Aspirin to elderly who is at risk of thrombosis, why?(1)

Answer 18

Aspirin is anti-pain and fever at high dose, and just anti-platelet at low dose

Question 19

Why steroid and montelukast are both effective in relieving asthma?

Answer 19

Steroid prevent AA formation so downstream leukotrienes are no produced. Montelukast act on leukotriene R so its bronchoconstriction effect is not expressed.

Question 20

Why COX2 inhibitor is desirable in pain killing? (3)

Answer 20

It prevents gastric ulcer, renal failure, thrombotic risk associated with steroid and non-selective NSAID