Association of the uric acid-to-high-density lipoprotein cholesterol ratio with uric acid stones: a single-center retrospective cohort study.

BACKGROUND: Uric acid stones (UAS) are a common metabolically associated subtype of urolithiasis. Their formation is strongly driven by acidic urine and frequently coexists with dysglycemia and other cardiometabolic abnormalities. The serum uric acid-to-high-density lipoprotein cholesterol ratio (UHR) is a readily available composite index reflecting uric acid burden and high-density lipoprotein (HDL)-related metabolic status. However, evidence linking UHR to composition-confirmed UAS in clinical practice remains limited. This study aimed to investigate the association between UHR and UAS. METHODS: We retrospectively reviewed hospitalized patients who underwent stone-related surgery at a single center from October 2023 to December 2025. Postoperative stone composition was determined by Fourier-transform infrared spectroscopy (FTIR). UAS were defined when a uric acid-related component was the predominant stone component. UHR was calculated after converting serum uric acid and high-density lipoprotein cholesterol (HDL-C) to mg/dL, using the formula UHR (%) = [uric acid (mg/dL)/HDL-C (mg/dL)] × 100, and was analyzed as a continuous variable per 5-unit increase. Binary logistic regression was performed to evaluate the association between UHR and UAS. The multivariable model adjusted for age, sex, body mass index (BMI), diabetes mellitus (DM), hypertension, urinary pH, and urea. Exploratory DM-stratified models were adjusted for age and urinary pH, with Firth penalized logistic regression performed as a sensitivity analysis. Complete-case analysis was used for regression. RESULTS: Overall, 485 patients were included. After excluding 23 patients with missing data required to calculate UHR, 462 complete cases (58 UAS) were analyzed in regression models. Compared with non-UAS patients, those with UAS had lower urinary pH and higher UHR. In the fully adjusted model, higher UHR was independently associated with greater odds of UAS [per 5-unit increase: odds ratio (OR) 1.64, 95% confidence interval (CI): 1.20-2.24]. In DM-stratified analyses, the association remained significant in both the non-DM subgroup (OR 1.74, 95% CI: 1.26-2.41) and the DM subgroup (OR 2.54, 95% CI: 1.37-4.71), with consistent findings in Firth sensitivity analyses. CONCLUSIONS: In a surgically treated cohort with FTIR-confirmed stone composition, higher UHR was independently associated with UAS and remained significant across DM strata. Given its routine availability, UHR may help prompt targeted metabolic evaluation in stone formers; prospective multicenter studies are warranted to validate its clinical utility.