288b thrombocytopenia

Question 1

SLE RBC antibody (anti-coagulation) effect? PTT test effect?

Answer 1

causing clotting

increases PTT, mixing test doesn’t fix - opposite effect of antibody against F VIII (which causes bleeding and increased PTT plus a low F VIII)

Question 2

thrombopoietin (TPO)

Answer 2

aa from liver - stimulates c-Mpl receptor on megakaryocytes –> platelet production

Question 3

TPO receptor pathway

Answer 3

receptor –> JAK-P (non-receptor tyrosine kinase) –> STAT pathway

Question 4

ITP - autoimmune thrombocytopenia - what is the pathogenesis?

Answer 4

CD4+ t-cells detect GP IIb/IIIa on platelet membrane –>

B cells produce IgG autoantibodies –>

platelet destruction via Mo in speel and liver (can remove spleen for Rx)

Question 5

ITP - autoimmune thrombocytopenia - acute vs chronic?

Answer 5

acute - kids, virus infection –> cross reacting Ab

chronic - adults, idiopathic usually but can be HIV, Hep C, H pylori

Question 6

ITP - autoimmune thrombocytopenia - presentation?

Answer 6

bleeding –> petechiae, mucosal, intracranial hemorrhage

Question 7

ITP - autoimmune thrombocytopenia - labs and dx?

Answer 7

clinical dx –> isolated thrombocytopenia - normal WBC, RBC count

Question 8

Rituximab - target?

Answer 8

anti-CD20 antibody on B cells –> Fc-mediated B cell lysis

usually used for lymphoma

Question 9

drug induced thrombocytopenia

Answer 9

chemo drugs

drug induced platelet antibodies

HIT

Question 10

Heparin induced thrombocytopenia (HIT) - pathogenesis?

Answer 10

PF4 from platelets + Heparin –> IgG autoantibodies –> thrombus + low platelets

Question 11

Heparin induced thrombocytopenia (HIT) - Rx?

Answer 11

discontinue heparin/LMWH

use direct thrombin inhibitor –> argatroban, lepirudin

Question 12

Argatroban, bivalirudin - target? rx for what?

Answer 12

direct thrombin inhibitors

used for HIT

Question 13

Romiplostim?

Answer 13

TPO receptor agonist –> increases platelet production