Therefore, we initiated plasma exchange (PE) for the patient. plasma exchange (PE) for the patient. Subsequently, she fulfilled the pediatric SLE diagnostic criteria, and ADAMTS13 activity was shown to be decreased and the anti-ADAMTS13 antibody titer increased. She was thus diagnosed with acquired TTP caused by SLE. Treatment response was good as a platelet count and ADAMTS13 activity improved with three times of PE, followed by methylprednisolone pulse therapy and administration of mycophenolate mofetil. Renal pathology showed thrombus formation in glomerular arterioles and lupus nephritis categorized as Class III (A) of the International Society of Nephrology and the Renal Pathology Society classification. Because the patient was thought to be in the high-risk group of SLE, three courses of intravenous cyclophosphamide pulse therapy were administered as an additional induction therapy. No recurrence of TTP was observed. Conclusion In SLE-related TMA, measurement of ADAMTS13 activity and the anti-ADAMTS13 antibody titer are necessary for diagnosis, and for predicting prognosis and recurrence of the disease; however, in the acute phase of immune-mediated TMA, it is important to initiate proper treatments even before knowing the results to improve prognosis. infection; all test results were negative. Finally, we found that ADAMTS13 activity was decreased to 1% and the anti-ADAMTS13 antibody titer returned positive. TABLE 1 Laboratory findings on admission. Blood Count Biochemical Exam Ca9.0 mg/dLRF 11 IU/mL Urinalysis Hematocrit 25.3% TP6.9 mg/dL Ferritin 1109 ng/dL Anti-Sm Ab29.3 Color Brown Hemoglobin 8.8 g/dL Albumin4.5 g/dLGlucose76 mg/dL Apoptosis Inhibitor (M50054) Anti-SS-A Ab 119.9 pH6.0RBC307 106/L T-Bil 4.28 mg/dL T-Chol220 Apoptosis Inhibitor (M50054) mg/dLAnti-SS-B AbNegative Proteinuria 4+ WBC4300/LD-Bil0.35 mg/dLTG108 mg/dLAnti-RNP AbNegative Hematuria Apoptosis Inhibitor (M50054) 3+ Platelet 0.8 103/L VWF AST 238 U/L Anti-ds-DNA Ab 179 IU/mL Glucose- Schistocyte 83/1000 ALT 171 U/L Serological Exam PR3-ANCA 1.0 U/mL Ketone 2+ LDH 1431 U/L CRP0.25 mg/dLMPO-ANCA 1.0 U/mLWBC- Hemostasis ALP929 U/L Haptoglobin 8 mg/dL LANegative RBC 35/HPF PT108%CK78 U/L CH50 14 U/mL Anti-CL AbNegativeEpitherial cast 1/LPFPT-INR0.97BUN25 mg/dLC370 mg/dLO-157 LPS AbNegativeGranular cast 1/LPFAPTT27.6 sCreatinine0.54 mg/dL C4 5.0 mg/dL Hyaline cast 1/LPFFibrinogen308 mg/dLeGFR94.3 mL/min/1.73 m2IgG1048 mg/dLDirect coombsNegative Pro/Cr 8.34 g/g Cre FDP 11.1 g/mL Na138 mEq/LIgA118 mg/dLBlood typeO Rh(+) D-dimer 4.3 g/mL K4.0 mEq/LIgM62 mg/dL Fecal Test Apoptosis Inhibitor (M50054) Cl103 mEq/LASLO94 IU/mL ADAMTS13 act 1 % CultureNegative ANA 80 Anti-ADAMTS13 Ab 1.4 BU/mL VerotoxinNegative Open in a separate window hospital day. After two courses of MPT, the anti-ADAMTS13 antibody test result was negative, the ADAMTS13 activity increased, and the platelet count rapidly increased (Figure 1A). Additionally, urinary findings were normal after the first course of pulse therapy. Mycophenolate mofetil (MMF, 1,000 mg/day) and hydroxychloroquine (HCQ, 200 mg/day) were administered for SLE. Since she was considered to be in the high-risk group of SLE organ damage, and TMA is known to have frequent complications of psychiatric symptoms (4), she was additionally treated with three courses of intravenous cyclophosphamide pulse therapy [IVCY, 580 mg/dose (500 mg/m2)] as induction therapy for SLE (Figure 1B). After the three courses of IVCY, leukopenia, mainly in lymphocytes, was observed; therefore, MMF was discontinued temporarily. HCQ was discontinued because color blindness and retinopathy were suspected during a regular ophthalmologic visit. After 1 year and 4 months since the onset, belimumab (BLM) was administered instead just after BLM had become under health insurance coverage for SLE pediatric patients (Figure 1B). Open in a separate window FIGURE 1 Clinical course. The upper graph shows the activity of TTP, and the lower graph shows the disease activity of SLE and lupus nephritis, both in (A,B). (A) Clinical course for the first 31 days after admission is shown. Three courses of plasma exchange (PE) were effective to remove anti-ADMTS13 antibody (ADMTS13inh) and to increase a platelet count (Plt) rapidly. However, 30 mg of prednisolone (PSL) injection and fresh-frozen plasma (FFP) infusion were not sufficient to suppress antibody production to recover ADAMTS13 activity (ADAMTS13act) and to maintain the platelet count. After two courses of methylprednisolone pulse therapy (MPT), the recovery of the ADAMTS13 activity and the platelet count was observed. Proteinuria disappeared after the first course of pulse therapy. Renal biopsy was performed on the 25th hospital day. (B) Overall clinical course is shown. Treatment details and clinical data are shown following (A). Apoptosis Inhibitor (M50054) Since the patient was considered to be in the high-risk group of SLE organ damage, and TMA is known to have frequent complications of psychiatric symptoms, she was additionally treated with three courses of intravenous cyclophosphamide pulse therapy (IVCY) as.