Disorders of Primary Hemostasis (Disorders of Platelets) Flashcards
Decreased plt production.
Inherited.
Cause: Lack of adequate bone marrow, Megakaryocytes, Congenital.
Lab Findings: Large plts, Dohle bodies, thrombocytopenia, normal plt function.
May Hegglin Anomaly
Acquired.
Decreased plt production.
Cause: From radiation, drugs (chemotherapeutic), ethanol, viruses.
Lab: Thrombocytopenia.
Acquired Thrombocytopenia
Immune.
Increased plt destruction.
Autoimmune disorder where antibodies bind to plts, shortening lifespan.
Acute: Disease of children (2-4 years old).
Usually follows viral infection.
Spontaneous remission.
Lab:
Immune thrombocytopenic purpura (ITP)
Aka: idiopathic thrombocytopenic purpura.
Immune.
Increased plt destruction.
Alloantibodies stimulated during pregnancy directed against fetal plts.
Lab: Decreased plt count in fetus.
Epidemiology: Pregnant women who lack platelet specific antigen but who inherit antigen recessively from father.
Neonatal Alloimmune Thrombocytopenia (NAIT)
Immune.
Increased plt destruction.
Heparin complexes with plts to prevent clotting.
Lab: No bleeding, can have normal plt count, and it’s normally not below 100x10^9/L.
Epidemiology: Heparin therapy patients.
Heparin Associated Thrombocytopenia (HAT)
Immune.
Increased plt destruction.
IgG antibody against heparin-plt complexes.
Lab: Associated with bleeding, and plt count below 100x10^9/L.
Epidemiology: Heparin therapy pts.
Heparin Induced Thrombocytopenia (HIT)
Non-immune.
Increased plt destruction.
Commonly found in children. Secondary to bacterial infection (90% of cases caused by shigella dysenteriae or E coli), toxins from bacteria attach to glomerulus and cause thrombi.
NO neurological manifestations: Abdominal problems.
Lab: Hemolytic anemia, poikilocytosis, schistocytes, renal failure, thrombocytopenia.
PT: normal or slightly prolonged
APTT: normal
Hemolytic Uremic Syndrome (HUS)
Non-immune.
Increased plt destruction.
Women more than men, 50% have virus infection in previous years.
Thrombotic lesions on arterioles and capillaries use up available plts. Results in thrombus in organs.
Neurological manifestations.
Abdominal problems.
Lab: Hemolytic anemia, thrombocytopenia, polychromasia, retics, schistocytes, All coag tests normal.
Thrombotic Throbocytopenic Purpura (TTP)
Non-immune.
Increased plt destruction.
Patients with bacterial/viral infection, pregnant women, burn patients, cancer pts, transfusion/transplant pts, injured pts.
Clotting mechanisms are activated throughout the body instead of in a localized area. Caused by sepsis, injury, burns, pregnancy, transfusions, etc.
Lab: Prolonged PT, APTT, TT, increased FDP and D-dimer, decreased fibrinogen and plt count, schistocytes.
Disseminated Intravascular Coagulation (DIC)
Myeloproliferative disorders, neoplastic stem cell disorder.
Lab: Increased megakaryopoiesis with thrombocytosis.
>1000x10^9/L, hemorrhaging from nose, gums, GI.
Essential Thrombocytosis (ET)/Primary
Caused by another condition: iron deficiency, surgery, blood loss, childbirth, inflammation, disease, malignancy, splenectomy.
Lab: 450-800x10^9/L with normal morphology
Reactive Thrombocytosis (RT)/ Secondary
Disorder of plt adhesion.
Hereditary.
Defect in GPIb/IX complex for plt adhesion so plts cannot interact with vWF.
Lab: Giant plts. Normal to low plts, increased BT, **Plt aggregation test is abnormal with ristocetin (ristocetin requires vWF and GPIb).
Plt aggregation test normal with ADP, collagen, epinephrine.
Bernard-Soulier disease (aka giant plt syndrome)
Disorder of plt aggregation.
Hereditary.
Deficiency of the GPIIb/IIIa complex, plts adhere but don’t aggregate because fibrinogen cannot bind.
Lab: Normal plt count, increased BT, Plt aggregation abnormal with ADP, Collagen, and epinephrine.
Plt aggregation normal with ristocetin.
Plt morphology normal.
Glanzmann’s Thrombasthenia
