Platelet disorders

Question 1

Gold standard in HIT diagnosis

Answer 1

Serotonin release assay

Question 2

Treatment of HIT

Answer 2

Stop heparin and give thrombin inhibitor such as lepiruidin or argatroban.

Question 3

Difference between Type 1 and Type 2 HIT

Answer 3

Type 1 occurs due to a non immune direct effect of heparin on platelet activation and usually presents within the first 2 days of heparin exposure. The platelet count the normalizes with continued heparin and there are no clinical consequences. Type 2 HIT is a more serious immune mediated disorder due to antibodies to platelet factor 4 complexed with heparin. This leads to platelet aggregation, thrombocytopenia, and thrombosis (both arterial and venous). Platelet counts usually drop >50% from baseline. Usually presents 5-10 days after initiation of heparin therapy and may lead to life threatening consequences.

Question 4

5 findings that point to TTP

Answer 4

Thrombocytopenia, hemolytic anemia, renal failure with clinical findings of AMS and low grade fever. Nearly all pts will also demonstrate increased # of schistocytes on peripheral blood smear

Question 5

Why do pts with DIC have hypofibrinogenemia?

Answer 5

Many inflammatory conditions cause increased production of fibrinogen since fibrinogen functions as an acute phase reactant. Thus, a plasma fibrinogen level within the normal range may represent significant consumption for that patient despite being in the normal range.

Question 6

Primary lab differences between DIC and TTP

Answer 6

In TTP, the PT, aPTT, fibrinogen and D dimer are normal.