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Thrombocytopenia

Thrombocytopenia. Checkpoint Primary Hemostasis. It’s about vasculature It’s about platelets It’s about maintaining blood in a fluid state within the blood vessels and preventing excessive blood loss after vascular injury Bottomline Platelet Abnormalities –

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Thrombocytopenia

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  1. Thrombocytopenia

  2. Checkpoint Primary Hemostasis • It’s about vasculature • It’s about platelets • It’s about maintaining blood in a fluid state within the blood vessels and preventing excessive blood loss after vascular injury Bottomline Platelet Abnormalities – QUANTITAIVE OR QUALITATIVE result in bleeding Graphic accessed URL http://www.uv.es/~vicalegr/CLindex/CLvasculitis/vasleu11.jpg , 2005.

  3. Primary Skin petechiae purpura ecchymoses Mucous membranes nose bleeds sclera gums Secondary Tissues Joints Clinical ManifestationsPrimary v.s. Secondary Disorders of Hemostasis http://heme-coag.uthscsa.edu/wwwbleed97/22apet.gif

  4. Platelet-Associated Disorders • Quantitative – Numbers game • Increased = thrombocytosis • >450,000/ml • Decreased = thrombocytopenia • <150,000/ml http://www.mcl.tulane.edu/classware/pathology/Krause/ET/RM1.html http://lifesci.rutgers.edu/~babiarz/Histo/Blood/Smear2.jpg http://www.ispub.com/xml/journals/ijid/vol3n2/vivax-fig1.jpg

  5. Thrombocytopenia Definition • Thrombocytopenia is defined as a platelet count less than 150,000 • 2.5 percent of the normal population will have a platelet count lower than this

  6. Bleeding • Surgical bleeding: less than 50,000 • Spontaneous bleeding: less than 10,000 to 20,000 • Severe life threatening bleeding: less than 6000

  7. Thrombocytopenia

  8. Differential • Pseudothrombocytopenia • Decreased Production- suggested by: • other cytopenias • normal sized/small platelets suggest a reduced bone marrow response to need • Increased Destruction- suggested by: • Microangiopathic blood picture (fragmented RBCs, high LDH) • Large platelets on smear • Associated autoimmune disease

  9. Pseudothrombocytopenia • If blood sample is inadequately anticoagulated, platelet clumps can be counted as WBC’s • 0.1% of patients have EDTA dependent agglutinins leading to platelet clumping and pseudothrombocytopenia • Can also be seen after administration of abciximab • If platelet clumping is observed, repeat the count using heparin or citrate as anticoagulant

  10. Decreased platelet production • In almost all disorders caused by marrow suppression or damage, white cell and red cell production are also affected. • Viral infections- rubella, mumps, varicella, parvovirus, hepatitis C, EBV • Direct megakaryocyte damage-HIV • Post chemotherapy or radiation therapy • Acquired bone marrow hypoplasia- Fanconi anemia, acquired pure megakaryocytic aplasia • Direct alcohol toxicity • B12 or folate deficiency

  11. Increased Platelet destruction • ITP and SLE- mechanism presumed to be presence of autoimmune anti-platelet Abs • Alloimmune destruction- posttransfusion, post- transplantation • Hypersplenism • Disseminated intravascular coagulation • TTP- HUS • HELLP in pregnant women • Medications- heparin, quinine, valproic acid • Infections- EBV, CMV, sepsis • Physical destruction during cardiopulmonary bypass, intravascular or intracardiac metastatic lesions

  12. Pathophysiology of ITP O Autoantibody Production AP Platelet Opsonization O Platelet Destruction D AP D Platelet Production P T-Cell–Mediated Cytotoxicity TC P TC

  13. Diagnosis • Repeat lab • Peripheral smear • Coagulation study • Fibrinogen, d-dimer • ITP- presumptive diagnosis if history, physical examination, complete blood count, and examination of the peripheral blood smear do not suggest other etiologies. • Bone marrow biopsy- unexplained thrombocytopenia severe enough to constitute a risk for major bleeding

  14. History • Recent viral or rickettsial infection • Previously diagnosed hematologic disease • Nonhematologic diseases known to decrease platelet counts (eg, eclampsia, sepsis, DIC, anaphylactic shock, hypothermia, massive transfusions) • A positive family history of bleeding and/or thrombocytopenia • Recent live virus vaccination • Poor nutritional status, especially in the elderly and alcoholics • Medications • Pregnancy, especially late in the third trimester or at onset of labor • Recent organ transplantation from a donor sensitized to platelet alloantigens • Recent transfusion of a platelet-containing product in an allosensitized recipient

  15. Physical exam • Petechiae — pinhead sized, red, flat, discrete lesions often occurring in crops in dependent areas • Purpura — purplish discoloration of the skin due to the presence of confluent petechiae. • Ecchymoses — nontender areas of bleeding into the skin, usually associated with multiple colors, due to the presence of extravasated blood

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