1. Thrombocytopenia
Allen Chang, PGY2
5/18/15

2. Learning Objectives Understand the mechanisms causing thrombocytopenia
Learn the workup of thrombocytopenia
Understand when to transfuse platelets

3. Case 1
A 24 year old woman is evaluated for a 1 day history of epistaxis and a new onset rash on her shins. Last week, her menses were abnormally heavy. Vital signs are normal. She has bruising over the shins and wrists and a petechial rash over the shins and abdomen.
Laboratory studies:
Hemoglobin g/dL
MCV fl
Platelet count 8,000/uL
WHAT IS GOING ON? DOCTOR! DO WE TRANSFUSE?
Ask interns to run through their thought process with this patient. What are the different broad categories of thrombocytopenia?

4. Thrombocytopenia
Thrombocytopenia is a platelet count less than 150,000.
There may be no symptoms and low platelets may simply found on routine CBC OR patients may bleed profusely
Platelet counts at are associated with mucocutaneous bleeding and less than 10 is associated with spontaneous intracerebral hemorrhage.

5. Classification of Thrombocytopenia
Increased Destruction
ITP, HIT, DIC, TTP/HUS, Medications
Decreased Production
Vitamin B12 / Folate deficiency, Bone marrow failure or invasion, aplastic anemia, Fanconi anemia, Medications
Sequestration
Hypersplenism (from Cirrhosis, heart failure, hepatic venous thrombosis, malignancy, infections)
Ask interns about the differential diagnosis for each category.

6. Pseudothrombocytopenia
How do you eliminate pseudothrombocytopenia?
Recheck CBC in an EDTA tube
Platelet clumping tricks the automated platelet counters into thinking that there are fewer platelets.

7. Medications Commonly Associated with Thrombocytopenia
Penicillins
Carbamazepine
Gold compounds
Heparin
Phenytoin
Rifampin
Sulfonamides
Vancomycin
Valproic Acid
Antiplatelet antibodies? No. Not recommended. Sensitivty of 49-66% and specificity of 78-92%. Negative test result does not rule out the diagnosis.

8. DITP – Drug induced thrombocytopenia GT – Gestational Thrombocytopenia
Slide from Stasi, R. Hematology How to approach thrombocytopenia 2012; 2012:
DITP – Drug induced thrombocytopenia
GT – Gestational Thrombocytopenia
Evans syndrome – autoimmune disease in which the patients antibodies attack their own RBCs and platelets, similar to AIHA and ITP
Roberto Stasi Hematology 2012;2012:
©2012 by American Society of Hematology

9. INDICATIONS FOR TRANSFUSION
PLATELET COUNT
Stable, no bleeding
<10
Stable, non bleeding and temperature of > 100.4
<20
Major surgery or invasive procedure, no active bleeding
< 50
Ocular surgery or neurosurgery, no active bleeding
< 100

10. Case 1 Revisited Do we transfuse?
A 24 year old woman is evaluated for a 1 day history of epistaxis and a new onset rash on her shins. Last week, her menses were abnormally heavy. Vital signs are normal. She has bruising over the shins and wrists and a petechial rash over the shins and abdomen.
Laboratory studies:
Hemoglobin g/dL
MCV fl
Platelet count 8,000/uL
Do we transfuse?

11. Take Home Points
Thrombocytopenia is caused by sequestration, increased destruction or increased production
Rule out Pseudothrombocytopenia by repeating a CBC in an EDTA tube.
Magic numbers are <10, <20 and <50
Transfuse regardless if platelets less than 10
Transfuse temperature is >100.4 if platelets are less than 20
Transfuse if patient is to have a surgery or procedure if platelets are less than 50

12. References ACP, MKSAP 16 Hematology/Oncology
George, J. ITP in adults: initial treatment and prognosis, UpToDate, Waltham, MA 2015
Liumbruno G, Bennardello F, Lattanzio A, Piccoli P, Rossetti G; Italian Society of Transfusion Medicine and Immunohaematology (SIMTI) Work Group. Recommendations for the transfusion of plasma and platelets. Blood Transfus. 2009;7(2):132–150.
Stasi, R; How to approach thrombocytopenia. American Society of Hematology Education Book. 2012: