Thrombotic Thrombocytopenic Purpura
Pathology – microangiopathic (small vessel) hemolytic anemia 2/2 deficiency of ADAMTS13 (cleaves ultra large vWF into smaller subunits)
High associated w/ HIV AIDS
4% have classic pentad (fever, anemia, thrombocytopenia, renal dysfunction, neurologic sequelae)
Ddx – Atypical HUS, HIT, ITP, DIC, tick borne illness, HELLP, macroaniopathy
Labs you should obtain: Dimer, fibrinogen, haptoglobin, LDH, PTINR, PTT, peripheral smear (schistocytes)
Management
Plasmapheresis (plasmic score to determine if empiric plasmapheresis is indicated while awaiting ADAMTS13 level [can take weeks])
High dose steroids
+/- rituximab (suppresses anti-ADAMTS13 production)
+/- caplacizumab – inhibits vWF interaction with platelets
+/- aspirin if plt > 50k
***Hold platelet transfusion – increased risk for thrombosis
Plasmic Score (https://www.mdcalc.com/calc/10200/plasmic-score-ttp)
Validated w/ metaanalysis to risk stratify pts and determine need for empiric treatment. Yes = 1 point
Platelets < 30k
Evidence of hemolysis
Cancer (no = point)
Transplant (no = point)
MVC < 90
INR < 1.5
Cr < 2
6-7 points – high risk
5 – intermediate
0-4 – low risk
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