Blood Bank / Transfusion / Coag

Question 1

Describe the pathophysiology of H.I.T. and include the significance of lab testing for it. Finally, what alternative treatment should be given for acute anticoagulation

Answer 1

heparin binds and alters PF4 exposing a neoantigen, and new abs form against it. These opsonize the PF4 in plasma, and then the Fc region binds to platelets and acitvates them causing aggregation and thrombosis.

We can measure these anitbodies, but a signficant proportion of all patients on heparin will develop abs, but few develop thrombocytopenia and even fewer thrombosis.

A more specific, but less sensitive test is the serotonin release assay (pt plasma is incubated with special radiolabeled serotonin containing platelets and heparin (if there are activitating abs in the pt plasma, then you will read out the serotonin)

Give direct thrombin inhibitors (argatroban or hirudin derivatives) instead of heparin

Finally, the 4Ts are degree of thrombocytopenia (50% fall, nadir >20) timing (5-10 days), thrombosis, no other causes

Question 2

Review the main clues for Hgb electrophoresis:
clues to beta thal minor?
Hgb AS vs transfused Hgb SS?
Ftrs of HgbCC or AC or CS?

Presence of HbS, but with a higher proportion of HbA than HbS:
Presence of HbS and HbF, but no HbA:
Overall higher proportion of HbS than HbA and HbF:
Presence of HbC, but with a higher proportion of HbA than HbC:
Presence of HbC and HbF, but no HbA:
A higher proportion of HbC than HbA:
Presence of HbS and HbC:
Presence of HbH:
Increased HbA 2:
Increased HbF:

List the order of electrophoresis peaks for Acid and Base gels

Answer 2

clues to beta thal minor? - increased Hgb A2

Hgb AS vs transfused Hgb SS? - AS will have Hgb A > HgbS (if A

Question 3

Describe the testing results for the different types of vWD:

Answer 3

Type 1 - F8, vWF ag, Ristocetin cF activity, and RIPA are all low. Normal multimer electrophoresis

Type 2A, B, M - all are again low, except for B the RIPA is increased (due to gain of function mutation) - for 2A large and intermed multimers are gone, for 2B large multimers are gone, and for 2M multimers are normal

*note: 2b patients get thrombocytopenia and DDAVP is contraindicated

Type 2N - Factor 8 decreased, but everything else, vWF ag, Ristocetin coF, and RIPA, and multimers are all normal (often misdiagnosed as hemophilia A)

Type 3 - everything is really low, and multimers are absent

All are autosomal dominant except for type 3and type 2N (AR)

Question 4

Deficiencies of what factors will prolong the PTT, but will not cause an increase in bleeding?
Conversely, what factor deficiency will have normal PT, PTT, but cause bleeding?

Answer 4

Deficiencies of Factor XII, prekalikrein, and HMWK (PTT increased, no increased bleeding risk)

Deficiency of factor XIII –> PT/ PTT NORMAL! but severe bleeding problems

Question 5

Explain how platelet aggregation studies are performed, list the activators used, and describe the key findings for: 1) vWD, 2) Bernard-Soulier, 3) Glanzmann’s 4) Storage pool disease

Answer 5

PRP is induces with ADP or epi, collagen, and ristocetin

vWD - normal aggregation with ADP, epi, and collagen, DECREASED with ristocetin

Bernard-Soulier - normal aggregation with ADP, epi, collagen, ABSENT with ristocetin (dependent of GpIb)

Glanzmann - ABSENT aggregation with ADP, epi, collagen, and NORMAL with ristocetin - on FLOW there will be absent CD61 (= GpIIb/IIIa)

Storage pool disease - normal or mild decrease for ADP, epi, and collagen, normal for ristocetin (on EM, absent dense granules)

Question 6

What are the predominant factors in cryoprecipitate and how is it made?

Answer 6

fibrinogen, vWF, and factor 8 (VIII)
made by simply chilling plasma, and then these things tend to precipitate out.
(This is why coag tubes can’t be put on ice or cooled, because they will artificially decrease these factor levels in plasma)

Question 7

Describe the mech of heparin and LMWH. Include their effects on lab tests
Also how do we measure The effects of low molecular weight heparin

Answer 7

UNfractionated heparin activates ATIII which will inhibit thrombin and Xa - It mostly affects the PTT, but with enough the PT will also be effected.

LMW heparin tends to mostly just inhibit factor Xa. The PTT can be prolonged or normal (not that sensitive to it).

To measure LMW heparin activity (if required) there is an anti-factor Xa assay (chromogenic) that can be performed.

Question 8

What are the vitamin K dependent coagulation factors?

Answer 8

2(thrombin), 7, 9, 10 and Protein C & S

Question 9

What blood type has the lowest level of vWF?

Answer 9

Blood type O