To define the risk of laboratory abnormalities associated with commonly prescribed medications in the context of urinary stone disease (USD).

We used the Veterans Health Administration Corporate Warehouse to identify adults ≥ 18 years with an index episode of USD. The development of laboratory abnormalities for those ever versus never on preventive pharmacological therapy was then compared using separate Cox proportional hazards regression models for each laboratory abnormality-drug class combination, adjusting for baseline patient characteristics and time-varying medication use over the study period. To provide a sense for absolute risk, we then used the models to estimate 2-year predicted probabilities of developing a laboratory abnormality for each.

Thiazide use was associated with a risk of: hypokalemia (hazard ratio [HR], 2.85; 95% confidence interval [CI], 2.66-3.05), hyponatremia (HR 1.41, 95% CI: 1.24-1.60), and hypercalcemia (HR 2.04, 95% CI: 1.70-2.46). Potassium citrate was associated with a risk of hyperkalemia (HR 1.44, 95% CI: 1.23-1.69). Allopurinol was associated with a risk of cytopenia (HR 1.17, 95% CI: 1.02-1.33). No significant association was observed between thiazide use and hyperglycemia or allopurinol use and transaminitis. The greatest absolute risk was for hypokalemia with thiazide use: a 2-year predicted probability of 17.3%.

Preventive pharmacological therapy for USD is associated with an increased risk of a variety of laboratory abnormalities, with the greatest absolute risk being hypokalemia with thiazides at over 1 in 6 patients. The study findings provide guidance for laboratory monitoring while on these therapies.