title: Acute oxalate nephropathy associated with orlistat.
abstract: BACKGROUND
  Obesity is a major world-wide epidemic which has led to a surge of various weight loss-inducing medical or surgical treatments. Orlistat is a gastrointestinal lipase inhibitor used as an adjunct treatment of obesity and type 2 diabetes mellitus to induce clinically significant weight loss via fat malabsorption.
  
  
  METHODS
  We describe a case of a 76-year-old female with past medical history of chronic kidney disease (baseline serum creatinine was 1.5-2.5 mg/dL), hypertension, gout and psoriatic arthritis, who was admitted for evaluation of elevated creatinine, peaking at 5.40 mg/dL. She was started on orlistat 120 mg three times a day six weeks earlier. Initial serologic work-up remained unremarkable. Percutaneous kidney biopsy revealed massive calcium oxalate crystal depositions with acute tubular necrosis and interstitial inflammation. Serum oxalate level returned elevated at 45 mm/l (normal <27). Timed 24-hour urine collection documented increased oxalate excretion repeatedly (54-96 mg/24 hour). After five renal dialysis sessions in eighth days she gradually regained her former baseline kidney function with creatinine around 2 mg/dL. Given coexisting proton-pump inhibitor therapy, only per os calcium-citrate provided effective intestinal oxalate chelation to control hyperoxaluria.
  
  
  CONCLUSIONS
  Our case underscores the potential of medically induced fat malabsorption to lead to an excessive oxalate absorption and acute kidney injury (AKI), especially in subjects with pre-existing renal impairment. Further, it emphasizes the importance of kidney biopsy to facilitate early diagnosis and treatment.
authors.affiliation: Department of Medicine, University of Mississippi Medical Center, Jackson, Mississippi, USA.
authors.forename: Youshay
authors.initials: Y
authors.lastname: Humayun
authors.affiliation: Department of Medicine, University of Mississippi Medical Center, Jackson, Mississippi, USA.
authors.forename: Kenneth C
authors.initials: KC
authors.lastname: Ball
authors.affiliation: Department of Pathology, University of Mississippi Medical Center, Jackson, Mississippi, USA.
authors.forename: Jack R
authors.initials: JR
authors.lastname: Lewin
authors.affiliation: Department of Anesthesiology, University of Mississippi Medical Center, Jackson, Mississippi, USA ; Simulation and Interprofessional Education Center, University of Mississippi Medical Center, Jackson, Mississippi, USA.
authors.forename: Anna A
authors.initials: AA
authors.lastname: Lerant
authors.affiliation: Department of Medicine, University of Mississippi Medical Center, Jackson, Mississippi, USA.
authors.forename: Tibor
authors.initials: T
authors.lastname: Fülöp
keywords: Acute kidney injury; Dialysis; Orlistat; Oxalate nephropathy; Proton-pump inhibitor; Weight loss supplement