Thrombocytopenia

Question 1

definition: thrombocytopenia

Answer 1

less than 150k platelets

Question 2

what is the regulator of platelet production?

Answer 2

thrombopoietin

Question 3

what are the three general causes of thrombocytopenia?

Answer 3

1. underproduction
2. destruction
3. sequestration (loss)

Question 4

which medications / drugs can cause thrombocytopenia?

Answer 4

1. chemotherapy agents

2. alcohol

Question 5

what are the three subcategories of underproduction causing thrombocytopenia?

Answer 5

1. destruction of megakaryocytes
2. inadequate precursor elements
3. marrow replacement

Question 6

what is the primary mechanism of pernicious anemia?

Answer 6

underproduction / ineffective production of precursors (B12)

Question 7

what are the megakaryocyte levels in pernicious anemia?

Answer 7

normal or increased (trying to make more platelets)

Question 8

what is a confirmatory test for pernicious anemia?

Answer 8

methylmalonic acid

Question 9

what are the features of immune (idiopathic) thrombocytopenic purpura (ITP)?

Answer 9

1. accelerated destruction of platelets
2. normal or increased megakaryocytes
3. antiplatelet antibodies (IgG usually) - destroyed by spleen

Question 10

what is the first line of defense in ITP treatment?

Answer 10

IV steroids (splenectomy is curative)

Question 11

what are the features of heparin induced thrombocytopenia?

Answer 11

1. immune mediated destruction of platelets

2. antibodies form in response to heparin and platelet specific PF4 complex

Question 12

pancytopenia is usually due to what cause?

Answer 12

underproduction

Question 13

what is the most common cause of thrombocytopenia due to underproduction?

Answer 13

medications

Question 14

for every unit of blood what is the increase in platelets?

Answer 14

5000

Question 15

underproduction is usually associated with decrease in how many cell lines?

Answer 15

two or more