Renal arcuate vein microthrombi-associated AKI.

BACKGROUNDS AND OBJECTIVES:This report describes six patients with AKI stages 2-3 (median admission creatinine level, 2.75 mg/dl [range, 1.58-5.44 mg/dl]), hematuria (five with hemoproteinuria), and unremarkable imaging with an unusual and unexplained histologic diagnosis on renal biopsy. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS:The patients were young adults who presented to two neighboring United Kingdom nephrology centers over a 40-month period (between July 2010 and November 2013). Four were male, and the median age was 22.5 years (range, 18-27 years). Their principal symptoms were flank pain or lower back pain. All had consumed alcohol in the days leading up to admission. RESULTS:Renal biopsy demonstrated microthrombi in the renal arcuate veins with a corresponding stereotypical, localized inflammatory infiltrate at the corticomedullary junction. All patients recovered to baseline renal function with supportive care (median, 17 days; range, 6-60 days), and none required RRT. To date, additional investigations have not revealed an underlying cause for these histopathologic changes. Investigations have included screening for thrombophilic tendencies, renal vein Doppler ultrasonographic studies, and testing for recreational drugs and alcohol (including liquid chromatography-mass spectrometry of urine) to look for so-called designer drugs. Inquiries to the United Kingdom National Poisons Information Centre have identified no other cases with similar presentation or histologic findings. CONCLUSIONS:Increased awareness and additional study of future cases may lead to a greater understanding of the underlying pathophysiologic mechanisms that caused AKI in these patients.