Philadelphia—Based on a new study, pharmacists should consider cautioning patients taking specific oral antibiotics that their risk for kidney stones might be increased.

A report in the Journal of the American Society of Nephrology recently pointed out the risk for the first time, noting that likelihood is greater at younger ages—i.e., children and adolescents—and among patients newly exposed.

“The overall prevalence of kidney stones has risen by 70 percent over the past 30 years, with particularly sharp increases among adolescents and young women,” pointed out lead author Gregory E. Tasian, MD, MSCE, a pediatric urologist at Children’s Hospital of Philadelphia. Tasian noted that while kidney stones generally have been a rare finding in children “The reasons for the increase are unknown, but our findings suggest that oral antibiotics play a role, especially given that children are prescribed antibiotics at higher rates than adults,” added coauthor Michelle Denburg, MD, MSCE, a pediatric nephrologist.

To reach their conclusions, the researchers analyzed data from the United Kingdom— health records of 13 million adults and children seen by general practitioners in the Health Improvement Network between 1994 and 2015. Prior antibiotic exposure was documented for nearly 26,000 patients with kidney stones, compared with nearly 260,000 control subjects.

The study determined the association between 12 classes of oral antibiotics and nephrolithiasis. Results indicated that five of the classes were associated with a diagnosis of kidney stone disease:
• Oral sulfa drugs
• Cephalosporins
• Fluoroquinolones
• Nitrofurantoin
• Broad-spectrum penicillins

“Exposure to any of five different antibiotic classes 3–12 months before index date was associated with nephrolithiasis,” the study team reported, adding that the adjusted odds ratio (95% confidence interval) was 2.33 (2.19 to 2.48) for sulfas, 1.88 (1.75 to 2.01) for cephalosporins, 1.67 (1.54 to 1.81) for fluoroquinolones, 1.70 (1.55 to 1.88) for nitrofurantoin/methenamine, and 1.27 (1.18 to 1.36) for broad-spectrum penicillins.

That means that, after adjustments for age, sex, race, urinary tract infection, other medications, and other medical conditions, patients who received sulfa drugs were found to be more than twice as likely as those not exposed to antibiotics to have kidney stones. For broad-spectrum penicillins, the study notes, the increased risk was 27% greater.

In addition, exploratory analysis documented that the magnitude of associations was greatest for exposure at younger ages (P <0.001) and 3 to 6 months before index date (P <0.001), with all but broad-spectrum penicillins remaining statistically significant 3 to 5 months from exposure.

“Oral antibiotics are associated with increased odds of nephrolithiasis, with the greatest odds for recent exposure and exposure at younger age,” the study authors conclude. “These results have implications for disease pathogenesis and the rising incidence of nephrolithiasis, particularly among children.”