Bleeding Disorders - Ch. 14 Flashcards
Petechiae and purpura, normal PT and PTT, normal platelet count
Bleeding due to abnormalities in vessel walls
Major infection that can cause vasculitis, DIC, and abnormal bleeding
Meningococcemia (N. meningitidis)
Ehlers-Danlos syndrome
Collagen defect –> microvascular bleeding
Vitamin C deficiency, bleeding
Scurvy –> collagen defect, microvascular bleeding
Cushing syndrome, bleeding
Excessive corticosteroid production –> protein wasting –> loss of perivascular support tissue –> microvascular bleeding
***Hereditary hemorrhagic telangiectasia (W-O-R syndrome)
AD, mutations cause TGF-beta signaling abnormalities, causing dilated tortuous blood vessels that bleed easily (nose, tongue, mouth, eyes, GI tract)
Henoch-Schonlein purpura
Systemic immune IgA nephropathy/vasculitis disorder – immune complex deposition –> rash/palpable purpura, colicky abdominal pain, polyarthralgia, acute glomerulonephritis
4 general causes of thrombocytopenia
- Decreased production
- Decreased survival
- Sequestration
- Dilution
Things that may selectively affect/inhibit megakaryotyes, causing thrombocytopenia
Cytotoxic drugs, thiazide drugs, alcohol, measles, HIV
Things that may decrease platelet production due to BM failure
B12 or folate deficiency, aplastic anemia, myelodysplastic syndrome, metastatic cancer, granulomatous disease, leukemia
A woman is pregnant, but the fetus has very few platelets. Cause?
Alloantibodies - the baby’s platelets are destroyed by antibodies in the mother
A person with a mechanical heart valve has anemia and thrombocytopenia. Why?
Heart valve can cause damage to both RBCs and platelets
A patient receives a blood transfusion and develops thrombocytopenia. Why?
Platelets die over time in stored blood, so the patient’s platelet concentration is diluted with transfusion
Large spleen + thrombocytopenia
Spleen can sequester platelets, causing thrombocytopenia
Autoantibody destruction of platelets, bleeding
Immune thrombocytopenic purpura
3 causes of secondary chronic ITP
- SLE
- HIV
- B cell neoplasms (CLL)
Antibodies against platelet glycoproteins 2b-3a or 1b-IX
What antibody type?
Immune thrombocytopenic purpura
IgG
Adult woman under 40, petechiae in skin and mouth, history of easy bruising, nose bleeds, and hemorrhaging after minor trauma. Menorrhagia and melena. Spleen appears normal, no LAD is noted.
Idiopathic chronic ITP
Adult woman under 40, petechiae in skin and mouth, history of easy bruising, nose bleeds, and hemorrhaging after minor trauma. Menorrhagia and melena. Splenomegaly and lymphadenopathy are notable.
Secondary chronic ITP - B-cell neoplasm
Thrombocytopenia, increased megakaryocytes in the marrow, large platelets in the blood, normal PT and PTT
Accelerated platelet destruction, causing increased thrombopoiesis
Child, recently had an upper respiratory viral illness, now presents with thrombocytopenia, petechiae, and purpura. PT and PTT are normal. Increased megakaryocytes in the marrow.
Acute ITP
Drugs that cause thrombocytopenia via antibody recognition
Quinine, quinidine, vancomycin, heparin