Changes in 24-hour Urine Chemistry in Patients with Nephrolithiasis during Weight Loss with Glucagon-Like Peptide-1 Based Therapies

Abstract

Background: Obesity is an independent risk factor for incident and recurrent nephrolithiasis. The impact of weight loss through glucagon-like peptide 1 (GLP-1) receptor agonists and dual GLP-1/ gastric inhibitory polypeptide receptor agonists (GLP-based therapies) on nephrolithiasis is not well-understood. This study examined the changes in 24-hour urine chemistry assessing for stone risk during weight loss through GLP-based therapies. Methods: This retrospective analysis identified adult stone formers followed at our academic institution’s weight wellness clinic between September 2015 and August 2023 and included patients with at least two 24-hour urine collections for stone risk assessment. 24-hour urine parameters before and during weight loss in patients on GLP-based therapies were compared. Results: Forty-four obese patients with nephrolithiasis experienced significant weight reduction (-6.6±7.3 kg, p<0.001) over a median 1.1 years of follow-up with GLP-based therapies. During this period, there was a significant decrease in 24-hour urine oxalate (40±16 to 32±11 mg/day, p=0.002), sulfate (21±10 to 17±9 mmol/day, p=0005), and ammonium (35±22 to 29±15 mEq/day, p=0.01). There were non-significant changes in urine calcium, citrate, uric acid, pH, phosphorus, sodium, potassium, magnesium, chloride, creatinine or total volume. Additionally, there was no statistical difference in urine supersaturation indices with respect to calcium oxalate, calcium phosphate and uric acid. Conclusion: Our results indicate that weight loss through GLP-based therapies is not associated with pro-lithogenic changes in 24-hour urine chemistry in patients with nephrolithiasis, unlike what happens with other weight loss modalities.