Atypical hemolytic uremic syndrome: a case report

Thrombotic microangiopathy is a pathological condition comprised of microvascular thrombosis involving any organ of the body leading to thrombocytopenia, Coombs-negative hemolytic anemia, and end-organ damage. The most common forms of thrombotic microangiopathies are Shiga toxin-producing Escherichia coli-mediated hemolytic uremic syndrome, thrombotic thrombocytopenic purpura, and atypical hemolytic uremic syndrome. The atypical hemolytic uremic syndrome occurs due to genetic and acquired mutations in complement regulatory factors and to complement activation factors in the immune system, mainly the alternative pathway. Clinical manifestations and outcomes differ with the prevalent mutations of the patient. Currently, available treatment modalities are therapeutic plasma exchange and a monoclonal antibody against C5, eculizumab. We report a case of a Sri Lankan girl diagnosed with atypical hemolytic uremic syndrome complicated with septicemia, hemolytic anemia, acute kidney injury, pulmonary hemorrhage with respiratory failure, and hypertension who had a complete remission following long-term (30 months) therapeutic plasma exchange. A 15-year-old Sri Lankan girl was transferred from a local hospital with the features of septicemia and acute kidney injury for specialized management. She had high blood pressure (180/100 mmHg) on admission. She underwent appendicectomy based on suspicion of acute appendicitis as the cause of sepsis. Following surgery, her condition deteriorated, and intensive care unit management was warranted because she developed pulmonary hemorrhages and respiratory failure requiring mechanical ventilation and renal replacement therapy in the form of hemodialysis. Her blood investigations showed microangiopathic hemolytic anemia, thrombocytopenia, elevated lactate dehydrogenase, and reduced human complement C3 levels, together with a normal coagulation profile. She was diagnosed with atypical hemolytic uremic syndrome and was initiated on therapeutic plasma exchange and other supportive therapy, including corticosteroids. Following a lengthy course of plasma exchange, complete recovery was achieved. The atypical hemolytic uremic syndrome is a rare disease entity requiring a high index of suspicion to diagnose. It is a diagnosis of exclusion. Early diagnosis with prompt treatment will render a better outcome. The atypical hemolytic uremic syndrome needs to be considered in all patients with thrombotic microangiopathy.