Platelet Disorders Flashcards
Bernard-Soulier syndrome platelet count
-/decrease
Bernard-Soulier syndrome bleeding time
increase
defect in platelet plug formation ->
increase bleeding time
platelet abnormalities ->
micro hemorrhage: mucus membrane bleeding, epistaxis, petechiae, purpura, increase bleeding time, possibly decreased platelet count
Bernard-Soulier syndrome mechanism
defect in platelet plug formation
large platelets
Bernard-soulier syndrome comments
decrease GpIb -> defect in platelet-to-vWF adhesion
abnormal ristocetin test that does not correct with mixing studies
Glanzman thrombasthenia platelet count
–
Glanzmann thrombasthenia bleeding time
increase
Glanzmann thrombasthenia mechanism
defect in platelet intern αIIb ß3 (GpIIb/IIIa) -> defect in platelet-to-platelet aggregation, and therefore platelet plug formation
Glanzmann thrombasthenia labs
blood smear shows no platelet clumping
HUS platelet count
decrease
HUS bleeding time
increase
HUS characterized by
thrombocytopenia, microangiopathic hemolytic anemia, and acute renal failure
HUS presentation
typical HUS seen in children, accompanied by diarrhea and commonly caused by Shira-like toxin of EHEC
HUS in adults does not present with diarrhea; EHEC infection not required
immune thrombocytopenia platelet count
decrease
immune thrombocytopenia bleeding time
increase
immune thrombocytopenia mechanism
anti-GpIIb/IIIa antibodies -> splenic macrophage consumption of platelet-antibody complex
may be primary or secondary to autoimmune disorder, viral illness, malignancy, or drug reaction
immune thrombocytopenia labs
increase megakaryocytic on bone marrow biopsy
immune thrombocytopenia treatment
steroids, IVIG
rituximab or splenectomy for refractory ITP
TTP platelet count
decrease
TTP bleeding time
increase
TTP mechanism
inhibition or deficiency of ADAMTS 13 (vWF metalloprotease) -> decrease degradation of vWF multimers
TTP pathogenesis
increase large vWF multimers -> increase platelet adhesion -> increase platelet aggregation and thrombosis
TTP labs
schistocytes, increase LDH, normal coagulation parameters
TTP symptoms
FAT RN
pentad of Fever, microangiopathic hemolytic Anemia, Thrombocytopenia, Renal failure, Neurologic symptoms
TTP treatment
plasmapheresis, steroids
von willebrand disease platelet count
normal
vWD bleeding time
increase
vWD PT
normal
vWD PTT
normal or increased
vWD mechanism
intrinsic pathway coagulation defect: decrease vWF -> increase PTT (vWF acts to carry/protect factor VIII)
defect in platelet plug formation: decrease vWF -> defect in platelet-to-vWF adhesion
autosomal dominant
vWD treatment
desmopressin, which releases vWF stored in endothelium
DIC platelet count
decrease
DIC bleeding time
increase
DIC PT
increase
DIC PTT
increase
DIC mechanism
widespread activation of clotting -> deficiency in clotting factors -> bleeding state
causes of DIC
Sepsis (gram negative), Trauma, Obstetric complications, acute Pancreatitis, Malignancy, Nephrotic syndrome, Transfusion
(STOP Making New Thrombi)
DIC labs
schistocytes, increase fibrin degradation products (D-Dimers), decrease fibrinogen, decreas factors V and VIII
