Precipitous AKI due to acute renal artery thrombosis in a patient with protein s deficiency

ABSTRACT

Introduction: Renal arterial thrombosis and infarction is an under-recognized condition due to its rarity and ability to mimic other disease processes. It can lead to secondary hypertension, acute kidney injury, and chronic kidney disease. Clinical manifestations include nausea, vomiting, flank pain, and sudden elevations in blood pressure. Here, we present a case of a patient with previous normal kidney function presenting with a severe AKI due to an acute renal arterial thrombus. Case Description A 58-year-old woman with previously normal kidney function (baseline Cr of 0.8 mg/dL) presented with complaints of nausea and vomiting and was found to have a stage 3 AKI with a creatinine of 4.65 mg/dL. Her creatinine level continued to rise, peaking at 8.5 mg/dL, despite volume expansion. Her urinalysis showed moderate blood and moderate protein. Her FeNa was calculated to be 6.5% and the P/creatinine was found to be 4.56 grams. Renal ultrasound revealed right renal atrophy and a normal appearing left kidney. She remained non-oliguric with good urine output and initially did not meet requirements for renal replacement therapy. Due to the unknown etiology of her AKI, a left kidney biopsy was performed which revealed fulminant acute cortical necrosis. Subsequently, an MRA revealed complete occlusion of the left renal artery. No angioplasty or stent placement was performed, and she eventually required renal replacement therapy. Hypercoagulable testing revealed protein S deficiency. Other serologic work up was negative. She was tested multiple times for COVID19 infection during her hospital stay and each test was negative. Discussion: The majority of renal thromboembolisms originate as emboli from the heart. Much less commonly, thrombi may form in the renal arteries themselves, especially in those with a hypercoagulable state such as this patient. In light of the recent global COVID19 pandemic, renal artery thromboembolism has gained increased recognition and prevalence. As such, our patient tested negative multiple times for COVID19 as a potential explanation for her hypercoagulable state. Acute renal artery thrombosis should be considered as an explanation for AKI of unknown etiology, especially in those who have underlying risk factors. In the appropriate context, imaging studies should be obtained promptly to prevent permanent kidney injury.