Successful treatment of an elderly frail patient with acquired idiopathic thrombotic thrombocytopenic purpura under close monitoring of ADAMTS13 activity and anti-ADAMTS13 antibody titers

A 68-year-old woman was admitted to the regional hospital because of hemolytic anemia, thrombocytopenia, and neurological abnormalities including unconsciousness. One week before admission, she suffered from diarrhea and subsequently passed out and hit her face on the ground. She was suspected of having TTP and was transferred to our hospital. We performed the assays of ADAMTS13 activity and anti-ADAMTS13 antibody titers, and confirmed the diagnosis of acquired idiopathic TTP with total deficiency of ADAMTS13 activity with its inhibitor. She was initially treated with plasma exchange combined with corticosteroids, however, we were forced to substitute plasma exchange with fresh frozen plasma infusion due to procedure-associated complications. The infusion of fresh frozen plasma was known as less effective and more likely to boost inhibitor titers compared to plasma exchange. In this circumstance, we could successfully switch the plasma therapy under close monitoring of ADAMTS13 activity and anti-ADAMTS13 antibody titers which precisely revealed the disease status of TTP in our patient, and eventually she achieved complete remission with normal level of ADAMTS13 activity and no inhibitor. Our experience suggested that the measurement of ADAMTS13 activity and inhibitor titer might be valuable not only for making the diagnosis but also for guiding treatment decisions by precise evaluating of disease status in patients with the acquired form of TTP.