Combining Acute Kidney Injury with Gastrointestinal Pathology: A Clue to Acute Oxalate Nephropathy.

Acute oxalate nephropathy (AON) is an increasingly recognized cause of acute kidney injury (AKI). Herein, we present two cases of biopsy-proven acute oxalate nephropathy in patients with gastrointestinal malabsorption, coincidentally both stemming from cholangiocarcinoma. The first is a 73-year-old male who presented with syncope and was found to have severe, oliguric AKI in the setting of newly diagnosed, nonresectable cholangiocarcinoma. The second is a 64-year-old man with remote resection of cholangiocarcinoma who presented after routine laboratory monitoring showed significant AKI. Temporary dialysis was required in both cases before renal recovery occurred. Together, these cases should increase physicians' suspicion of AON in the presence of malabsorption. By doing so, the workup of oxalate nephropathy can be expedited with prompt initiation of treatment.