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Kidney Week

Abstract: PO2228

Dual Diagnosis of Thrombotic Thrombocytopenic Purpura and Atypical Hemolytic Uremic Syndrome in Pregnancy

Session Information

Category: Women’s Health and Kidney Diseases

  • 2000 Women’s Health and Kidney Diseases

Authors

  • Dellapiana, Gabriela, Cedars-Sinai Medical Center, Los Angeles, California, United States
  • Gonzales, Savannah, Cedars-Sinai Medical Center, Los Angeles, California, United States
  • Burwick, Richard M., Cedars-Sinai Medical Center, Los Angeles, California, United States
Introduction

Thrombotic thrombocytopenic purpura (TTP) and atypical hemolytic uremic syndrome (aHUS) are thrombotic microangiopathy (TMA) disorders which may initially occur in pregnancy. TTP, caused by severe ADAMTS13 deficiency, is treated with plasma exchange (PEX); whereas aHUS, caused by uncontrolled complement activation, is treated with complement inhibition (e.g., eculizumab). Because TTP and aHUS have different causes, the term TTP-HUS is no longer used. However, we describe a patient diagnosed and treated for both TTP and aHUS in pregnancy.

Case Description

A 38-year-old female at 9 weeks’ gestation presented with hematuria. Labs revealed severe thrombocytopenia (platelets 5 k/μl), hemolytic anemia, and acute kidney injury. TTP was suspected, so PEX was initiated, but she did not fully respond (Fig 1). ADAMTS13 activity was low (11%) but with negative inhibitor, arguing against acquired TTP; genetic testing ruled out congenital TTP. Complement-mediated TMA (aHUS) was considered given low C3, C4, and proteinuria; Lupus and Anti-Phospholipid Syndrome were ruled out. Complement genetic testing revealed a rare C3 variant and polymorphisms in CFH and MCP, which are enriched in aHUS patients. After multidisciplinary review, the diagnosis of aHUS was made. PEX was stopped, and eculizumab was started with good response. At 35 weeks’ gestation she presented with hypertension and petechiae, and labs showed recurrence of hemolytic anemia and thrombocytopenia (platelets 7 k/μl). She had cesarean delivery, after which PEX was initiated given renewed concern for TTP. ADAMTS13 activity was <5% with positive inhibitory antibody, now confirming acquired TTP. Eculizumab was stopped, and she received 14 cycles of PEX, prednisone, and rituximab for refractory TTP (Fig 1). Treatments were stopped after 6 weeks, and she remains in remission after 1 year.

Discussion

This case illustrates dual diagnosis of TTP and aHUS in pregnancy. Key points: a) Rarely, TTP and aHUS may coexist; b) ADAMTS13 activity and complement genetic testing may help identify TMA etiology; and c) Treatment of TMA in pregnancy with PEX or complement inhibition should be clinically-based.

Clinical course