Background <p>Serum uric acid levels have been associated with albuminuria; nonetheless, the dose–response relationship has been insufficiently explored. This study aimed to characterize the shape of the dose–response relationship between the serum uric acid level and the urinary albumin-to-creatinine ratio in a nationally representative Korean adult population.</p> Methods <p>This cross-sectional study analyzed data from 15,823 adults included in the 2022–2024 Korea National Health and Nutrition Examination Survey. The dose–response curve was characterized using generalized additive models with smoothing splines. Separate analyses were conducted for normouricemic (serum uric acid level &lt; 7.0&#xa0;mg/dL) and hyperuricemic (serum uric acid level ≥ 7.0&#xa0;mg/dL) groups to determine whether the association differed across clinical ranges.</p> Results <p>Generalized additive models showed a nearly flat dose–response curve within the normouricemic range, followed by a marked upward trend in the hyperuricemic range. Serum uric acid levels were positively associated with the log-transformed albumin-to-creatinine ratio in the hyperuricemic group (β = 0.184; 95% confidence interval [CI]: 0.113 to 0.256). Stratified analyses revealed that this association was significantly amplified in participants with diabetes, reduced kidney function, and in non-obese individuals.</p> Conclusion <p>The association between serum uric acid levels and albuminuria appeared to exhibit a threshold-like effect, characterized by a marked increase specifically within the hyperuricemic range. These findings suggest that closer monitoring of serum uric acid may be relevant in hyperuricemic individuals with diabetes or reduced kidney function, although interventional studies are needed to determine whether urate-lowering therapy is beneficial.</p> Graphical abstract <p></p>