CAI Therapy in IIH Linked to Higher Kidney Stone Risk, Large Database Study Suggests

New research indicates that carbonic anhydrase inhibitors, commonly prescribed for idiopathic intracranial hypertension, may increase the risk of kidney stones, emphasizing the importance of monitoring and preventive care. Photo: University of Washington Medicine. Click image to enlarge. As the prevalence of idiopathic intracranial hypertension (IIH) continues to rise, carbonic anhydrase inhibitors (CAIs) such as acetazolamide remain a mainstay of medical management. However, new evidence suggests these medications may carry an increased risk of kidney stone formation.A recent retrospective cohort study published in Journal of Neuro-Ophthalmology examined more than 73,000 individuals with IIH to determine whether CAI therapy contributes to kidney stone development. Investigators compared 23,182 CAI-treated patients with 50,080 untreated controls and applied propensity score matching to balance demographic and clinical characteristics. After matching, each cohort included 22,464 patients.Kidney stone incidence, identified using ICD-10 codes, was assessed at three intervals: one year, one to two years, and two to three years. Across all periods, CAI use was associated with a significantly elevated risk. At one year, the risk ratio (RR) for kidney stone development among treated patients reached 1.49. The risk increased substantially between years one and two (RR: 2.24) and remained elevated even at two to three years (RR: 1.51).A sensitivity analysis focusing on patients taking at least 500 mg of acetazolamide daily mirrored this trend, with the highest long-term risk observed in the two-to-three-year span (RR: 2.18). Subgroup findings revealed notable demographic differences: males experienced higher risk, while Black or African-American patients had a lower risk of developing kidney stones.The study authors emphasized the clinical implications of these findings, noting that CAI therapy, while effective, may predispose certain patients to kidney stone formation. They reported that treated patients demonstrated a clearly increased risk compared with untreated controls. According to the authors, this is particularly important for individuals with a history of nephrolithiasis, who already face heightened susceptibility to recurrence.To help mitigate this risk, the researchers suggested several strategies clinicians may consider: monitoring calcium and vitamin D supplementation to avoid hypercalciuria; encouraging increased fluid intake to dilute urine and reduce risk of stone development; assessing urine pH before initiating therapy to identify those with preexisting risk factors; and implementing dietary changes or adjunctive treatments when appropriate.“In conclusion, although CAIs remain a cornerstone of IIH management, their potential to increase kidney stone risk necessitates a more tailored approach to prescribing these medications,” the study authors wrote in their Journal of Neuro-Ophthalmology paper. “By incorporating demographic-specific risk factors and proactive preventive measures, clinicians can better manage the safety and efficacy of IIH treatments, ultimately improving patient outcomes and quality of life.”Click here for the journal source. Muayad J, Alryalat SA, Al Deyabat O, et al. Assessing the Risk of Kidney Stone Development in Patients With Idiopathic Intracranial Hypertension Treated With Carbonic Anhydrase Inhibitors. J Neuroophthalmol. 2025;45(4):420-5. This article was developed by the editorial staff in conjunction with experts in the field. In the process, AI may have been among the editorial tools used to meet the goals of human editors, who approved all content.