Pathoma TidBits

Question 1

What factors lead to tumor invasion

Answer 1

Downregulation of E-cadherin leads to dissociation, attachment to laminin destroys basement membrane, attachment to fibronectin leads to local spread

Question 2

What is the first step of primary hemostasis? What is it triggered by?

Answer 2

Transient vasoconstriction, by neural stimulation and endothelin release from endothelial cells

Question 3

Through what receptor does platelet adhesion occur? Aggregation?

Answer 3

adhesion to vWF= GP1b. Aggregation: GPIIb/IIIa

Question 4

What two mediators do platelets release after binding to vWF?

Answer 4

ADP- promotes GPIIb/IIIa receptor exposure and TXA2 (COX derivative) to promote aggregation

Question 5

What’s the presentation of a patient with primary hemostasis disorder? When would you see petechiae?

Answer 5

Mucosal and skin bleeding: epistaxis, hemoptysis, GI, hematuria, menorrhagia; Quantitative disorders, not qualitative

Question 6

ITP is an autoimmune antibody against what?

Answer 6

IgG against GPIIb/IIa from plasma cells in spleen

Question 7

What are the lab findings in ITP: count, PT/PTT, cells

Answer 7

Low platelets, normal PT/PTT, inc megakaryocytes (from inc platelet production)

Question 8

What is caused by TTP? Where are thrombi common?

Answer 8

Autoantibody against ADAMS13 (divides multipers to monomers for degradation) leads to abnormal platelet adhesion; CNS

Question 9

How does HUS lead to platelet microthrombi?

Answer 9

E Coli 0157:H7’s verotoxin damages endothelial cells

Question 10

What are the labs in TTP/HUS: platelet count, bleeding time, PT/PTT,?

Answer 10

Thrombocytopenia, inc bleeding time, normal PT/PTT, anemia with schistocytes and megakaryocytes

Question 11

What is the effect of aspirin and uremia on platelets?

Answer 11

Aspirin, blocks COX, leads to no TXA2: platelet aggregation; uremia: adhesion and aggregation

Question 12

What’s the genetic GP1b def? What’s the important feature? GPIIb/IIIa def?

Answer 12

GP1b= Bernard-Soulier (big platelets); GPIIb/IIIa= Glanzmann

Question 13

How do secondary hemostasis disorders present generally?

Answer 13

Deep tissue bleeding into muscles and joints; re-bleeding after surgery

Question 14

Draw the coagulation cascade

Answer 14

INT: 12, 11, 9, 8. Ex: 7. Common: 10, 5, 2, 1.

Question 15

What activates each pathway? How is it measured?

Answer 15

Intrinsic: subendothelial collagen, PTT. Extrinsic: PT, tissue thromboplastin

Question 16

Cause of hemophilia A? B? How to differentiate between hemophilia A and anti-VIII?

Answer 16

A= Eight; B= Nine. Mixing study! PTT doesnt correct if Antibodies are present

Question 17

Labs in vWF def? Treatment?

Answer 17

Inc bleeding time (poor adhesion), inc PTT (vWF stabilies factor 8), abnormal ristocetin test. Desmopressin! It induces release from WP bodies

Question 18

How does Vit K assist coagulation?

Answer 18

It is activated by epoxide reductase (MOA of warfarin), and once activated gamma carboxylates II, VII, IX, X, C and S