Case Presentation: 23 years old female with history of lupus and Sjogren’s syndrome was sent to the hospital by her rheumatologist for worsening anemia, thrombocytopenia and kidney injury. Patient was recently admitted to the hospital for a pregnancy related lupus flare with hospital course complicated by diffuse alveolar hemorrhage, autoimmune hemolysis and nephrotic syndrome. She was treated with plasma exchange, cyclophosphamide, high dose steroids and her pregnancy was electively terminated. Her condition improved and she was discharged home with hydroxychloroquine. During the second admission, her labs revealed a hemoglobin of 6.5, platelets of 52k, Lactate dehydrogenase (LDH) 1000s, and low haptoglobin. Schistocytes were seen on the peripheral smear. TTP was unlikely as her recent ADAMTS13 activity was 56%. Decision was made to hold off on plasmapheresis and pulse dose steroids were started. Despite continued treatment with cyclophosphamide and high dose steroids her renal function and anemia continued to worsen requiring multiple blood transfusions. Disseminated intravascular coagulation was unlikely given normal fibrinogen levels. Infectious workup as well as Coomb’s tests were negative. Laboratory results continued to show high levels of LDH, low haptoglobin and persistent schistocytes on blood smear indicating progression of thrombotic microangiopathy (TMA). Based on these findings, diagnosis of atypical hemolytic uremic syndrome (aHUS) or complement mediated HUS (c-HUS) was made. Eculizumab, a monoclonal antibody to C5, was promptly started. Over the following 2 weeks, the patient’s renal function improved, hemolysis slowed down, and platelet counts improved. Her renal function, anemia and thrombocytopenia continue to improve following discharge.
Discussion: Atypical hemolytic uremic syndrome (aHUS) is defined by the simultaneous occurrence of microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury that is not caused by Shiga toxin. Major causes include complement gene mutations or antibodies to complement factor H, drug toxicity, autoimmune disorders, and pregnancy. The diagnosis of c-HUS is based on the classical triad findings of microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury, in the setting of complement dysregulation. It is important to rule out other life threatening etiologies such as TTP and DIC. Eculizumab is an effective treatment and should be started promptly as many patients with aHUS suffer from severe kidney injury requiring dialysis.
Conclusions: c-HUS is characterized by a triad of microangiopathic hemolytic anemia, thrombocytopenia and acute renal failure. This case illustrates the challenges in the diagnosis and management of c-HUS in a pregnant patient with acute lupus flare as many findings overlap with TTP, HELLP, DIC and other autoimmune processes. High suspicion should be raised for c-HUS after ruling out other more common etiologies and eculizumab should be promptly initiated to prevent progression to renal failure.
To cite this abstract:Chi, J; Newman, J; Mayo, P. NOT YOUR TYPICAL HUS: COMPLEMENT MEDIATED HEMOLYTIC UREMIC SYNDROME. Abstract published at Hospital Medicine 2018; April 8-11; Orlando, Fla. Abstract 521. https://www.shmabstracts.com/abstract/not-your-typical-hus-complement-mediated-hemolytic-uremic-syndrome/. Accessed February 21, 2020.