Proton-pump inhibitors associated with decreased urinary citrate excretion.

INTRODUCTION: Proton-pump inhibitors (PPIs) may increase the risk of kidney stone formation, but the mechanism has not been elucidated. There is a paucity of literature evaluating the effects of PPIs on urinary metabolites and urine pH.

METHODS: We performed a retrospective review of nephrolithiasis patients treated at our institution and compared patients who were taking PPIs to those who were not at the time of their 24-h urine collections. Hierarchical multivariate linear regression was used to evaluate the independent relationship between PPI use and urinary mineral composition.

RESULTS: We identified 301 consecutive patients, 88 (29%) of whom were taking PPIs at the time of their 24-h urine collections. Patients taking PPIs were older and more likely to have medical comorbidities associated with metabolic syndrome such as hypertension, diabetes, and dyslipidemia (p < 0.01). Controlling for these factors, patients taking PPIs were found to have 12% lower 24-h urine citrate excretion (β =  - 0.12, ΔF = 4.24, p = 0.04). There were no other differences in urinary mineral composition between the groups.

CONCLUSION: Our findings suggest that patients who take PPIs regularly may be at risk for decreased urinary citrate excretion. The consequent decrease in urinary citrate may become clinically significant for patients with other predisposing factors for hypocitraturia.