Orlistat-induced oxalate nephropathy may be dose-independent and present as a late manifestation

We present the case of a 61-year-old Caucasian male veteran who had been on orlistat (120mg dosing) for four years, and had changed to the over-the-counter (OTC) form, Alli (orlistat 60mg), about three months before presentation. He had been experiencing nausea and vomiting for three weeks prior to evaluation. Laboratory studies revealed a serum creatinine of 6.2 mg/dL--his previous renal function having been normal. An ultrasound-guided renal biopsy was performed, which revealed deposition of calcium oxalate crystals in the renal tubules. Orlistat is a popular weight-loss medication. Orlistat-induced oxalate crystal nephropathy has recently been reported in the literature, resulting from the original, patented version. We report a case with the first such complication from the OTC version, Alli - which is a reduced-dose formulation. Our case report highlights that this complication can occur after several years of use of the medication and is not necessarily dose dependant.