Flashcards in DIT Platelets Deck (18):
2 functions of vWF?
complex with factor VIII (if deficiency increases PTT)
Platelet adhesion to vessel collagen wall and other platelets (Deficiency causes longer bleeding time)
Platelets have thrombin. What does it do?
Fibrinogen to fibrin
Side effect of aspirin in kids?
Reye syndrome. Hepatoencephalopathy
Liver poblems and encephalopathy and hypoglycemia (b/c bad liver)
Platelet ADP receptors inhibitors?
How does it affect platelets
CLOPidogrel (has D and P in it)
No platelet aggregation b/c no aggregation b/c ADP receptor is what signals for GpIIbIIIa to be on cell surface
Glycoprotein IIb/IIIa inhibitors
Abciximab, eptiFIBatide, and tiroFIBan
Can't bind fibrinogen to crosslink platetes (fib in middle b/c mimics fibrinogen and interrupts binding site)
Symptoms of platelet disorders?
Microhemorrhages: bleeding from mucous membranes, epistaxis, petechiae (look like freckles), purpura
high bleeding time
Platelet disorders. Only 4 of them, but they are 4 Star
Cause of immune thrombocytopenia?
Anti-GpIIb/IIIa antibodies: spelenic macrophage eat the platelets (virus can trigger it)
Labs: megakaryocytic increased in marrow b/c trying to get platelet count back up
Tx: steroids or IVIG or splenectomy (can't store platelets in spleen so more in circulation)
What is cause of TTP?
Thrombotic thrombocytopenic purpura:
Platelets excessively activated B/c ADAMTS13 is deficient so can't break down vWF which causes large vWF which activates platelets.
Widespread thrombosis and results in thrombocytopenia. Results in purpura
Also: activation of coag cascade and excessive fibrin mesh: microangiopathic hemolytic anemia with schistocytes
What is HUS? what is triad?
Think of as milder version of TTP
Uremia (renal insifcciency)
What is pentad of TTP? Mnemonic
Nasty FEVER Torched His KIDNEYS
Neurological symptoms (headache, confusion, seizure, coma)
what is HUS associated with?
What is going on in Bernard Soulier syndrome?
Defect in Gp1b so can't bind vWF. There is "1b" in bernard
Platelets are enlarged and removed from circulation so result is slightly low platelet count
What is up in Glanzmann thrombasthenia?
GpIIb/IIa defect so no plaetelet aggregation.
Blood smear shows no platelet clumping
High BT, but normal PC
Thrombocytopenia caused by things that are not wrong with platelets?
Heparin induced thrombocytopenia
What is going on in von Willebrand disease?
Tx? NEED TO KNOW
Decreased vWF so less of its two functions . 1: platelet adhesion and factor 8 stabilization
Higher BT AND higher PTT!!!
It is common
Tx is weird: DDAVP (desmopressin) b/c it releases stored vWF from endothelium