Long‐Term Therapeutic Plasma Exchange Therapy as Effective Approach to Refractory Primary Acquired Pregnancy‐Related Thrombocytopenic Purpura

Abstract

Dear Editor, Thrombotic thrombocytopenic purpura (TTP) is a life-threatening thrombotic microangiopathy characterized by antibody-mediated deficiency of ADAMTS13 (a disintegrin and metalloproteinase with thrombospondin-like repeats) protease (1). Therapeutic plasma exchange (TPE) is the gold standard to treat acquired forms of TTP, highly effective in removing ADAMTS13 antibodies and supplying ADAMTS13 in the replacement plasma. There are no evidence-based guidelines for TPE during pregnancy and only few cases of pregnancyrelated TTP have been reported with positive outcomes for mother and child. We report the first case of a refractory primaryacquired pregnancy-related TTP that was successfully controlled with long-term TPE. A 27-year-old woman in her 25th week of gestation presented with headache, dizziness, petechial hemorrhages, and hematuria. She reported no fever or signs of infection. Peripheral blood counts revealed severe thrombocytopenia and anemia. Coagulation and kidney function tests were normal. Elevated lactate dehydrogenase, decreased haptoglobin, and fragmentocytes indicated intravascular hemolysis. The tentative diagnosis of TTP was made and daily TPE was initiated immediately. Subsequent laboratory data revealed ADAMTS13 antibodies and decreased ADAMTS13 activity supporting the TTP diagnosis. Thrombocytopenia is commonly seen during pregnancy and usually a benign, physiologic condition difficult to distinguish from pathologic causes (including TTP). Additionally, ADAMTS13 activity may be moderately reduced in pregnant women near term (2). However, severely reduced ADAMTS13 activity (<10%) and the presence of an inhibitory antibody together with hemolytic anemia and thrombocytopenia are highly specific for TTP (3). TPE was performed heparin-free using citrate anticoagulation via a central venous catheter (exchange volume of 40 mL/kg per session) accompanied by prednisone (1 mg/kg/day) under close monitoring of fetal Doppler heart rates and ultrasounds. Thrombocytes recovered and ADAMTS13 antibody levels dropped significantly (Fig. 1). We continued TPE until the thrombocyte count increased to normal range on two consecutive days and then stopped. However, thrombocyte counts decreased again by 50%. Heparin-induced thrombocytopenia was excluded. Assuming an early relapse of the disease we reconvened daily TPE.