Wednesday, August 12, 2015

Thrombotic Microangiopathies (TTP)

Chief Resident Morning Report

Today's case was a patient presenting with microangiopathic hemolytic anemia, most likely thrombotic thrombocytopenic purpura (TTP) on the basis of either congenital/acquired ADAMTS13 deficiency, or an experimental chemotherapy drug.

Important learning points:

-Pathophysiologically, TTP results from multimers of Von Willebrand Factor (I erroneously said platelets) due to congenital or acquired deficiency of the enzymes responsible for degrading said multimers, ADAMTS13
-The classical clinical pentad of fever, altered mental status/seizures, renal failure, thrombocytopenia, and hemolytic anemia is rarely seen all together.

-The alterations in mentation are often fluctuating changes in LOC rather than discrete focal neurologic symptoms.

-The condition is 100% fatal if left untreated, and treatment consists of plasmapheresis (PLEX) at a centre like ours, or steroids and fresh frozen plasma while en route to a centre like ours.

-There is a wide differential of thrombocytopenia, and we discussed immune thrombocytopenic purpura as a potential diagnosis of exclusion among other causes.

-Be careful committing someone to a diagnosis of Evan’s syndrome (ITP and autoimmune hemolytic anemia) without ruling out a microangiopathic cause such as TTP/HUS.

-We discussed blood film findings (fragments/Schistocytes) and laboratory findings of hemolysis.

Further Reading:

George, J. N., & Nester, C. M. (2014). Syndromes of thrombotic microangiopathy. New England Journal of Medicine371(7), 654-666.

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