Semaglutide and Kidney Stones: Uric Acid, Oxalate, and Stone Risk on GLP-1s

Written by Adam Maggio | Medically reviewed by Dr. James Whitfield, DO, FACOI

The rising popularity of semaglutide and other GLP-1 receptor agonists for weight loss and diabetes management has prompted questions about their p...

# Semaglutide and Kidney Stones: Uric Acid, Oxalate, and Stone Risk on GLP-1s

The rising popularity of semaglutide and other GLP-1 receptor agonists for weight loss and diabetes management has prompted questions about their potential impact on kidney stone formation. While these medications offer significant metabolic benefits, understanding their influence on urinary chemistry—specifically uric acid and oxalate—is crucial for patients with a history of nephrolithiasis or those at high risk.

The Indirect Link: Dehydration and GI Side Effects

Currently, there is no strong evidence to suggest that semaglutide directly causes kidney stones. However, the most common side effects of GLP-1 agonists—nausea, vomiting, and diarrhea—can lead to significant fluid loss. Dehydration is a primary risk factor for all types of kidney stones, as it concentrates the urine, allowing minerals to crystallize and form stones [1]. Therefore, the risk associated with semaglutide is largely indirect, emphasizing the critical need for adequate hydration during therapy.

Impact on Uric Acid

Uric acid stones account for a significant portion of kidney stones, particularly in individuals with obesity, insulin resistance, and type 2 diabetes—the very populations often prescribed semaglutide. Interestingly, GLP-1 receptor agonists may actually have a protective effect against uric acid stones.

Lowering Serum Uric Acid: Meta-analyses have shown that treatment with GLP-1 RAs is associated with a significant reduction in serum uric acid levels [2]. This reduction is likely secondary to improved insulin sensitivity and weight loss, which enhance the renal excretion of uric acid.

Urine Alkalinization: Insulin resistance is known to cause overly acidic urine, a major driver of uric acid stone formation. By improving insulin sensitivity, semaglutide may help normalize urine pH, making uric acid more soluble and less likely to precipitate into stones.

Considerations for Oxalate and Calcium Stones

Calcium oxalate stones are the most common type of kidney stone. The relationship between semaglutide and oxalate is more complex and less direct than with uric acid.

Obesity and Hyperoxaluria: Obesity itself is associated with increased urinary oxalate excretion (secondary hyperoxaluria). As semaglutide induces weight loss, it could theoretically reduce this risk factor over time.

Dietary Changes: The appetite-suppressing effects of semaglutide often lead to significant dietary changes. If a patient inadvertently increases their intake of oxalate-rich foods (like spinach, nuts, or certain berries) while eating less overall, their oxalate risk might increase. Conversely, a healthier, more balanced diet could lower the risk.

  • Urine Chemistry Studies: A study analyzing 24-hour urine chemistries in patients on GLP-1 agonists found no major worsening in the supersaturation of calcium oxalate, calcium phosphate, or uric acid [3]. This suggests that, chemically, the medications do not inherently create a more lithogenic (stone-forming) environment, provided hydration is maintained.

    • Overall Stone Risk and Clinical Implications

    Observational evidence suggests that GLP-1 receptor agonists might actually reduce the risk of recurrent kidney stones. A study found that patients with a history of nephrolithiasis who were prescribed GLP-1 RAs had a lower rate of repeat stone events compared to those not on the medication [4]. This protective effect is likely mediated through weight loss, improved glycemic control, and favorable changes in uric acid metabolism.

    For clinicians and patients, the key takeaways are:

  • Hydration is Paramount: The most significant risk factor for kidney stones while on semaglutide is dehydration secondary to gastrointestinal side effects. Patients must be counseled to maintain high fluid intake.
  • Potential Protective Effects: For patients with obesity and insulin resistance, the metabolic improvements from semaglutide may actually lower the risk of certain stones, particularly uric acid stones.
  • Individualized Monitoring: Patients with a strong history of calcium oxalate stones should continue standard preventative measures, including dietary oxalate management and adequate calcium intake, while monitoring their hydration status closely.

    • In summary, while semaglutide does not directly cause kidney stones, its side effects necessitate vigilant hydration. The overall metabolic benefits, however, may offer a protective advantage against stone formation in the long term.

    References

    [1] Can Ozempic Cause Kidney Stones? - https://www.findclearmatch.com/blog/can-ozempic-cause-kidney-stones

    [2] The effect of glucagon-like peptide-1 receptor agonists on serum uric acid - https://www.frontiersin.org/journals/endocrinology/articles/10.3389/fendo.2023.1320504/full

    [3] Effect of Glucagon-Like Peptide-1 Receptor Agonists on 24-Hour Urine Chemistry - https://pubmed.ncbi.nlm.nih.gov/39580252/

    [4] GLP-1 Receptor Agonists and the Risk of Recurrent Nephrolithiasis - https://www.auajournals.org/doi/10.1097/JU.0000000000004015.06