Bleeding Disorders Flashcards
What are the 4 steps to normal hemostasis (clot formation)?
- Vasoconstriction
- Platelet plug formation
- Coagulation cascade to stabilize clot
- Limit fibrin clot
If there is a primary hemostasis disorder that causes excessive bleeding, how is it likely inherited?
Autosomal Dominant (primary = platelet plug formation)
If there is a secondary hemostasis disorder that causes excessive bleeding, where are the bleeds usually located?
Joints - hemarthroses
4 types of bleeding disorders?
- Vessel wall abnormalities
- Reduced platelet number
- Reduced platelet function
- Clotting factor abnormalities
PT measures?
Extrinsic pathway (tissue factor + FVII)
PTT measures?
Intrinsic pathway
What is an example of a vessel wall abnormality that leads to excessive bleeding in the periorbital region?
Perivascular amyloid in myeloma
= periorbital bruising (raccoon eyes)
< 150K platelets
Thrombocytopenia
Symptoms for thrombocytopenia usually manifest at what number of platelets?
< 50K
Dangerous spontaneous bleeds with thrombocytopenia can occur when the number of platelets is below?
< 20K
What are 3 immune destruction disorders of platelets?
- HIV-associated thrombocytopenia
- Drug-induced thrombocytopenia
- Immune Thrombocytopenic Purpura (ITP)
HIV-associated thrombocytopenia suppresses bone marrow by?
Infecting hematopoietic stem cells
HIV-associated thrombocytopenia will produce _____ against platelets
Autoantibodies
Drug-induced thrombocytopenia via Myelosuppression occurs from?
Chemotherapy, Chloramphenicol and others
Drug-induced immune thrombocytopenia occurs from?
Quinidine, Vancomycin, Heparin
Heparin induced immune thrombocytopenia involves what cascade of events?
PF4 - Heparin complex activates IgG
- IgG binds to the Fc receptor and activates platelets
- Platelets are degraded by IgG
What happens with Immune Thrombocytopenic Purpura (ITP)?
Autoantibodies against platelets bind to platelets
- Macrophages destroy platelets
Acute form of Immune Thrombocytopenic Pupura occurs in?
Kids
Chronic form of immune thrombocytopenic purpura occurs in?
Young adult women
What are the symptoms seen with Immune Thrombocytopenic Purpura?
Petechiae, purpura, thrombocytopenia, platelet antibodies and increased megakaryocytes in marrow
Increased Megakaryocytes in the bone marrow could indicate?
Immune Thrombocytopenic Purpura
Treatment for Immune Thrombocytopenic Purpura?
Corticosteroids
IVIg
CD20 - rituximab
What are 2 Non-immune destruction disorders of platelets?
Thrombotic Thrombocytopenia Purpura (TTP)
Hemolytic Uremic Syndrome
Normally, what metalloproteinase converts multimers of vWF to smaller multimers?
ADAMTS13