Hemostasis / Thrombosis

Question 1

which clotting factor deficiency is not associated with a bleeding tendency?

Answer 1

factor XII (12)

Question 2

What 2 factors associated with severe bleeding in heterozygous state?

Answer 2

FXI and FVII deficiencies

Question 3

What is the treatment for FV & fibrinolytic factor deficiencies?

Answer 3

FFP

Question 4

What is the treatment of FII and X deficiencies?

Answer 4

Prothrombin complex concentrates(PCC)

Question 5

What is the treatment of FXIII and fibrinogen disorders?

Answer 5

Purified concentrates(FXIII and fibrinogen) or cryoprecipitate when concentrates not available

Question 6

What happen to fibrinogen when both PT and aPTT are prolonged?

Answer 6

Fibrinogen will be reduced or abnormal

Question 7

When thrombin time prolonged?

Answer 7

When fibrinogen is reduced or abnormal, in presence of inhibitors, presence of thrombin inhibiting drugs and hypoalbuminemia.

Question 8

What clotting factor deficiencies suspected if aPTT normalized in mixing studies?

Answer 8

FXII, FXI, FIX & FVIII

Question 9

If PT normalized in mixing study what factor deficiencies?

Answer 9

FVII

Question 10

If both PT and aPTT normalized in mixing studies?

Answer 10

FX, FV, FII and fibrinogen

Question 11

What is the screening test for FXIII deficiency?

Answer 11

Urea clot lysis assay except in newborn period may give false positive result and mild deficiencies better to use functional FXIII assays ( FXIII activity, antigen and FXIII A and B subunit)

Question 12

Where is vWF synthesized?

Answer 12

Megakaryocytes and endothelial cells

Question 13

What is the important of desmopressin(DDAVP) for vWF?

Answer 13

It induce the release of vWF from storage sites into plasma

Question 14

What bleeding disorder suspected with MSK bleed

Answer 14

Fibrinogen disorder, FX,FII and FXIII deficiencies

Question 15

What bleeding disorder common with GI and CNS bleeds?

Answer 15

FX deficiency

Question 16

What bleeding disorder suspected with umbilical cord bleed

Answer 16

Fibrinogen, FII, V, XIII deficiencies

Question 17

virchow’s triad

Answer 17

stasis
endothelial damage
hypercoagulability

Question 18

peds age groups at highest risk of thrombosis

Answer 18

newborns

adolescents

Question 19

what is the cause of purpura fulminans?

Answer 19

homozygous deficiency of protein C and/or S

Question 20

where are protein C and S made?

Answer 20

liver

Question 21

what are the antiphospholipid antibodies?

Answer 21

• lupus anticoagulant
• anti-cardiolipin antibodies
• anti-beta-2-glycoprotein I (beta2-GPI) antibodies

Question 22

definition of antiphospholipid syndrome

Answer 22

The presence of thrombosis or pregnancy loss with the persistent (2 tests performed 12 weeks apart) presence of APLA (LAC or ACLA or B2-GPI)

Question 23

what should you check in patients with MTHFR gene polymorphisms?

Answer 23

homocysteine level - if elevated, may be at increased risk of clot

Question 24

who should have thrombophilia testing

Answer 24

• unprovoked VTE
• recurrent VTE
• purpura fulminans
• fam hx of thrombophilia (may provide anticipitory guidance about starting prothrombotic meds etc)

Question 25

management of a child who you suspect has purpura fulminans

Answer 25

- test for protein C and S | - FFP 10-20ml/kg Q6-12 hr

Question 26

how to manage blocked CVC that needs removal

Answer 26

anticoagulation x 3-5 days prior to removal to minimize risk of embolization

Question 27

if a child presents with a PE, what should you look for?

Answer 27

DVT - 50% have extremity clot

Question 28

why does leukemia increase risk of thrombosis

Answer 28

increased thrombin generation

Question 29

what platelet counts are recommended for patients on anticoagulation?

Answer 29

> 50 for treatment | > 30 for prophylaxis

Question 30

three signs of RVT

Answer 30

- thrombocytopenia - palpable flank mass - hematuria

Question 31

patients that may not respond to treatment with unfractionated heparin

Answer 31

those with antithrombin (FII) deficiency

Question 32

how does unfractionated heparin work

Answer 32

binds and potentiates the effect of anti-thrombin

Question 33

pathophysiology of warfarin induced skin necrosis

Answer 33

acquired protein c deficiency

Question 34

vitamin K dependent coagulation factors

Answer 34

factor 2, 7, 9, 10 and protein C

Question 35

UFH target anti-Xa levels

Answer 35

0. 35-0.7 (aPTT 60-85 s) | - should use PTT when you have hyperbilirubinemia

Question 36

LMWH target anti-Xa levels

Answer 36

0.5-1.0

Question 37

target INR for mechanical valve

Answer 37

2.5-3.5

Question 38

treatment of DVT without risk factors

Answer 38

anticoagulate 9-12 months

Question 39

treatment of DVT with chronic risk factors

Answer 39

indefinite

Question 40

treatment of DVT with acute risk factors

Answer 40

x3 months, then switch to prophylaxis if risk factors still present

Question 41

what is warfarin induced skin necrosis

Answer 41

acquired protein C deficiency, occurs within 3-10 days of starting treatment with warfarin

Question 42

how can you test for HIT?

Answer 42

ELISA for anti-platelet factor 4 antibodies (high sensitivity, low specificity)

Question 43

components of the 4T score for HIT

Answer 43

- degree of thrombocytopenia < 50%, plts > 20 - timing of thrombocytopenia (5-10 days after starting heparin) - presence of new thrombosis - no other cause of thrombocytopenia

Question 44

diagnostic criteria for anti-phospholipid antibody syndrome

Answer 44

Defined by the presence of vascular thrombosis or pregnancy loss with the persistent (2 tests performed 12 weeks apart) presence of APLA (LAC or ACLA or B2-GPI)

Question 45

how do you test for a lupus anticoagulant? (3 steps)

Answer 45

1. Demonstrating an abnormal aPTT 2. Mixing study to show that it does not correct – due to presence of inhibitor 3. Confirmatory test – add phospholipids to prove that the abnormality is phospholipid dependent

Question 46

what is the INR

Answer 46

(patient's PT/control PT)to the power of ISI, where ISI = international sensitivity index (sensitivity of thromboplastin)

Question 47

list novel anticoagulants and their mechanism of action

Answer 47

Rivaroxaban/apixaban - oral factor Xa inhibitors Dabigatran - oral direct thrombin inhibitor

Question 48

reversal of warfarin - INR > 8 and significant bleeding

Answer 48

FFP, Prothrombin complex concentrates, recombinant factor VIIa

Question 49

reversal of warfarin - INR > 8, no bleeding

Answer 49

vitamin K (PO or IV)

Question 50

on what chromosome is vWF encoded?

Answer 50

chromosome 12

Question 51

where is vWF made and stored?

Answer 51

``` endothelial cells (stored in weibel-palade bodies) and megakaryocytes (stored in alpha granules) ```

Question 52

functions of vWF

Answer 52

- Platelet adhesion to injured endothelium via GPIb/IX and collagen - To assist with platelet aggregation via GPIIb/IIIa receptor - Carrier protein for F8 – protecting it from degradation by protein C

Question 53

inheritance of vWD

Answer 53

Type 1, Type 2 A/B/M - autosomal dominant Type 2N, Type 3 - AR

Question 54

factors which affect vWF levels

Answer 54

- ABO blood type (lower levels in Type O) - High estrogen states - Hypothyroidism (decreases levels of vWF) - Stress - Acute illness - DDAVP

Question 55

VWF/F8 concentrates

Answer 55

Humate-P Willate Alphanate

Question 56

Treatment options for VWD

Answer 56

- antifibrinolytics - estrogens (OCP) - DDAVP (Risk of hyponatremia, seizures - tachyphylaxis) - VWF/factor 8 concentrates - cryo

Question 57

conditions associated with acquired VWD

Answer 57

- Wilms tumour - Hypothyroid - SLE - Aortic stenosis - LVAD

Question 58

in what type of VWD is DDAVP contraindicated?

Answer 58

type 2B - can worsen thrombocytopenia