POS-202 ATYPICAL HEMOLYTIC UREMIC SYNDROME: A RARE CAUSE OF MALIGNANT HYPERTENSION AND ACUTE RENAL FAILURE IN ADULT

Abstract

Atypical hemolytic uremic syndrome (aHUS) is a form of complement-mediated thrombotic microangiopathy mainly characterized by excessive activation of alternative complement pathway activation. This occurs due to mutation in the complement regulatory proteins or by acquired neutralizing antibodies to these complement regulatory proteins. It is characterized by a triad of microangiopathic hemolytic anemia, thrombocytopenia and acute kidney injury. It usually has a poor prognosis in the absence of prompt recognition and treatment, with more than 50% of the patients progressing to end stage renal disease. Case report- A 21 year old male presented to emergency with sudden onset headache, blurring of vision and multiple episodes of vomiting. There was no history of diarrhea or dysentery in recent past.Thorough examination was done and investigations were performed. On examination, patient had pallor and elevated blood pressure of 200/100 mmHg. Relevant findings on investigations was anemia (hemoglobin: 8.9g/dl), thrombocytopenia (platelet count: 98000cells/cu.mm) and deranged renal function tests (BUN: 156, Creatinine: 7.4mg/dl). LFT showed raised total bilirubin: 2.4mg/dl with direct fraction 0.3mg/dl. LDH and uric acid were also raised(1131U/L and 9.5mg/dl respectively). Urine routine showed trace proteinuria and urine for active sediment was negative for cast. Ultrasound of bilateral kidneys showed normal echogenecity, normal size and a maintained corticomedullary differentiation with a normal renal artery Doppler study. Peripheral smear was suggestive of Normocytic normochromic anemia with occasional target cells, elliptical cells and fragmented RBC’s with a raised reticulocyte count of 6.6. With these reports, a probable diagnosis of hemolytic uremic syndrome was considered. Stool cultures for shiga toxin producing E.coli was negative. The patient had uncontrolled hypertension despite three antihypertensives, thrombocytopenia and renal failure worsened further and patient was initiated on dialysis. Kidney biopsy was done in view of rapidly progressing renal failure which showed prominent subendothelial edema with blood vessels showing mucoid edema with near complete obstruction of lumen of medium sized vessels suggestive of thrombotic microangiopathy with acute tubular necrosis (figure1). Serum C3 levels were significantly on lower side with near normal C4 levels. ADAMTS13 levels were within normal limits. Hence a diagnosis of atypical hemolytic syndrome was finally considered .The test for complement factor H antibody was negative. However further confirmatory investigations like genetic analysis of complement regulatory genes were unavailable. Patient was also started on daily sessions of plasma exchange therapy as eculizumab was not available due to financial constraints. Over next 10 days patients clinical condition started to stabilize with improvement in renal function, anemia and platelet count. Patient was discharged and advised to follow up with monitoring of renal function tests. In patients with hypertensive crisis, acute renal failure and thrombocytopenia, aHUS should be considered. Timely recognition of disease and prompt treatment is essential for favourable outcome. In the face of non-availability of eculizumab, plasmapheresis can be considered as initial treatment option.