Case Presentation: A 23-year-old female presented to the ED, 6 days postpartum with weakness, vomiting, and jaundice following a delivery complicated by preeclampsia. On examination, she had scleral icterus, and labs showed hemoglobin of 6 (normal 12.1- 15.1 g/dL), platelets of 8 (normal 150 – 400× 10^9/L), elevated LDH, low haptoglobin, and schistocytes, suggesting hemolysis. Creatinine was 2 mg/dl (up from baseline 0.5), and liver enzymes were mildly elevated. Urinalysis showed proteinuria and hematuria. After aggressive resuscitation, workup for acute kidney injury and hemolytic anemia/thrombocytopenia was initiated, including complement levels and ADAMTS13 testing. With a high PLASMIC score of 7, Thrombotic Thrombocytopenic Purpura (TTP) was suspected, and plasma exchange and steroids were started. Despite treatment, her platelet count remained low, and creatinine worsened.On Day 4, ADAMTS13 resulted as 78, excluding TTP. Complement levels were normal, and autoimmune workup was unremarkable, leading to the discontinuation of steroids. At this point, we planned for Eculizumab for suspected complement-medicated hemolytic uremic syndrome (aHUS) with first dose on Day 5. However, her creatinine worsened but she remained non-oliguric. A kidney biopsy was planned but was complicated by retroperitoneal bleed leading to cardiac arrest, but ROSC was obtained, and she underwent Emergent embolization. She was continued on weekly eculizumab and gradually stabilized. On Day 20 she was discharged and is currently doing well with normal creatinine and platelet levels, pending genetic testing.
Discussion: aHUS is a life-threatening condition often triggered by genetic mutations in complement regulatory proteins, with pregnancy increasing the risk due to amplified complement activation. Patients with genetic predisposition may have their first presentation during рrеgոаոϲy or рοstрartum. Since it may present similarly to HELLP syndrome and ТТP, and the differentiation is challenging. In our case, TTP was initially suspected, and she underwent plasma exchange. TTP was ruled out on day 4, and HELLP syndrome was considered less likely due to the late postpartum onset. Autoimmune conditions were excluded based on negative anti-nuclear antibody testing. As there is no single definitive testing for aHUS, anti-complement therapy should be started based on a presumptive diagnosis. In our case, after excluding TTP and SLE, eculizumab was initiated only on day 5. It is also important to note that plasma exchange and anti-complement therapy can be used concurrently when there is diagnostic uncertainty.Additionally, kidney biopsy revealed thrombotic microangiopathy but did not clarify the etiology, suggesting that biopsy is unlikely to provide diagnostic value in an acute setting.
Conclusions: Delaying anti-complement therapy in aHUS can result in permanent renal failure, lifelong dependence on hemodialysis, and can be life-threatening in the acute phase. Due to the diagnostic challenges and the time needed to confirm the diagnosis, clinicians must maintain a high index of suspicion for early intervention. Awareness of the association between pregnancy/postpartum states and aHUS can help prompt timely treatment. Furthermore, since plasma exchange and anti-complement therapy can be administered concurrently, there should be no delay in initiating anti-complement treatment while awaiting a definitive diagnosis.