The role of N-acetylcysteine in the treatment of thrombotic thrombocytopenic purpura.

Thrombotic thrombocytopenic purpura (TTP) is an acute, thrombotic microangiopathy with a high mortality rate if left untreated. Plasma exchange (PEX) is the current standard of care. However, a significant number of patients are refractory to this treatment. N-acetylcysteine (NAC) was recently suggested as a potential therapeutic adjunct for patients with TTP. This study reports a series of three patients with TTP successfully treated with NAC in addition to standard therapy. Detailed chart reviews on these patients were conducted. We discuss clinical features, laboratory findings and management of three patients who presented with microangiopathic hemolytic anemia and thrombocytopenia. Anti-ADAMTS13 antibodies and low levels of ADAMTS13 were detected and confirmed the diagnosis of acquired TTP. Based upon their severe presentation or lack of response to initial treatment with PEX, corticosteroids and other immunosuppressive agents, NAC was added. Under this combined treatment, all three patients hada significant clinical improvement of symptoms with concurrent normalization of platelet count and ADAMTS13 activity level. This report highlights the potential therapeutic utility of NAC in the treatment of TTP. Randomized controlled studies will be required to better characterize the risk-to-benefit ratio of NAC in the treatment of TTP.