Acute oxalate nephropathy associated with orlistat

Area of Science:

• Nephrology
• Pharmacology

Background:

• Obesity is a global epidemic driving demand for weight loss treatments.
• Orlistat, a lipase inhibitor, aids weight loss by reducing fat absorption.
• It's used adjunctively for obesity and type 2 diabetes management.

Observation:

• A 76-year-old female with chronic kidney disease developed acute kidney injury (AKI) after starting orlistat.
• Kidney biopsy showed calcium oxalate crystals, acute tubular necrosis, and inflammation.
• Elevated serum and urine oxalate levels confirmed hyperoxaluria.

Findings:

• Medically induced fat malabsorption from orlistat led to excessive oxalate absorption.
• This resulted in acute kidney injury, particularly in a patient with pre-existing renal impairment.
• Treatment involved dialysis and oral calcium-citrate for oxalate chelation.

Implications:

• Orlistat use can precipitate AKI through hyperoxaluria in susceptible individuals.
• Early diagnosis via kidney biopsy is vital for prompt management.
• This case highlights the importance of monitoring renal function in patients on orlistat, especially those with kidney disease.