Reversible acute renal failure as an atypical presentation of ischemic nephropathy

Ischemic nephropathy (IN) is defined as a clinically significant reduction in glomerular filtration rate in patients with hemodynamically significant obstruction to renal artery flow in a solitary functioning kidney or with bilateral renal artery stenosis (RAS). Ischemic nephropathy typically has a subacute to chronic course that may lead to end-stage renal disease. Acute anuric renal failure, which occurs less commonly with IN, is usually associated with moderately severe hypertension and has been attributed to certain risk factors: angiotensin-converting enzyme inhibition, a reduction in blood pressure secondary to antihypertensives or volume contraction, and exposure to contrast media. We present a series of six patients with IN and acute, anuric renal failure without either moderately severe hypertension or the previously defined risk factors. Of these six patients, four had RAS in a solitary kidney and two were found by ultrasound to have disparity in kidney size and bilateral RAS. Within 1 week of surgery, three patients developed renal failure that did not involve the kidney(s) responsible for the anuria and thus mimicked postoperative acute renal failure. Creatinine levels pre-anuria (1.2 to 2.1 mg/dL), during renal failure (5.0 to 12.8 mg/dL), and postrecovery (1.6 to 2.8 mg/dL) showed recovery of renal function, with renal artery bypass in four patients (sustained at 1 year). Two patients refused surgery and are on chronic dialysis. Acute renal failure in IN may occur postoperatively or spontaneously, and emergent intervention (ultrasound, angiography, angioplasty, and/or surgery) in this setting may lead to the correction of RAS and preservation of renal function.