Thrombocytopenia Allen Chang, PGY2 5/18/15

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

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 11.9 g/dL MCV 85 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?

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 20-50 are associated with mucocutaneous bleeding and less than 10 is associated with spontaneous intracerebral hemorrhage.

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.

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.

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.

DITP – Drug induced thrombocytopenia GT – Gestational Thrombocytopenia Slide from Stasi, R. Hematology How to approach thrombocytopenia 2012; 2012: 191-197 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;2012:191-197 ©2012 by American Society of Hematology

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

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 11.9 g/dL MCV 85 fl Platelet count 8,000/uL Do we transfuse?

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

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: 2012. 191-197