Complement-Mediated Thrombotic Microangiography Presenting as Hypertensive Emergency and Kidney Failure

Introduction: Hemolytic uremic syndrome (HUS) consists of hemolytic anemia, thrombocytopenia, and renal failure. It is a thrombotic microangiopathy (TMA) that leads to the formation of microthrombi that occlude microvasculature. “Atypical HUS” is labelled as TMA, divided by etiologies such as complement mediated (CM-TMA), drug induced TMA, coagulation-mediated TMA, etc. Once TMA is diagnosed, differentiating thrombotic thrombocytopenic purpura (TTP) and CM-TMA is vital for effective treatment. We present a young individual who presented with hypertension with further workup revealing CM-TMA. Case Description: 26 year old male with no known medical history presented to the emergency department from his optometrist’s office with papilledema and exudates. He had blurry vision and headache that began a few weeks prior. In the ED, he was noted to have hypertensive emergency with blood pressure (BP) at 260/160 and was started on a nicardipine drip. Initial labs revealed K 2.8 mg/dL, BUN 36 mg/dL, creatinine (Cr) 4.0 mg/dL, troponin 179 ng/L, Hgb 11.0, platelet count 95 mg/dL, and UA with 1+ protein, peripheral blood smear without schistocytes. Secondary workup including autoimmune serologies, ACTH level, renin:aldosterone ratio, ADAMTS13, and urine metanephrines were negative. CT Abdomen/Pelvis and renal US were negative. CT Head and MRI Brain were unremarkable. Renal biopsy was planned but not completed due to persistent hypertension. Patient also requested discharge due to financial limitations. Patient’s initial presenting symptoms improved, but he continued to have systolic blood pressures consistently above 150s. He was discharged on Carvedilol, Hydralazine, Nifedipine and Spironolactone. Renal biopsy was completed outpatient after optimization of BP which revealed “thrombotic microangiopathy with increased tubulointerstitial and glomerular disease most consistent with CM-aHUS”. He was started on ravulizumab-cwvz with improvement in his Cr and BP. Discussion: This case emphasizes the importance of a broad differential with hypertensive urgency and acute renal failure. CM-TMA tends to fall lower on the differential, however early diagnosis and treatment is essential for treatment and prevention of worsening renal failure. This case also highlights the importance of access to care and the financial burdens that may limit or delay treatment.