Ultrasound-detected renal surface nodularity and renal damage in hypertensive adults undergoing routine health screening: a cross-sectional study

Objectives To develop an ultrasound-based grading system for renal surface nodularity (RSN), assess its reproducibility, and evaluate its association with renal damage in hypertensive adults undergoing routine health screening. Methods This retrospective cross-sectional study included 871 hypertensive adults who underwent renal ultrasound during routine health screening between October 2025 and March 2026. RSN was graded from stored standardized coronal-plane images on a three-point scale: grade 0 (smooth), grade 1 (mild, undulating), and grade 2 (severe, serrated). Multivariable logistic regression was used to identify factors independently associated with RSN and to evaluate the association between RSN grade and renal damage, defined as eGFR < 60 mL/min/1.73 m² or proteinuria (≥ 1+), with sequential adjustment that included eGFR as a continuous variable in the final model. Results RSN was detected in 410 of 871 patients (47.1%): 226 (25.9%) had grade 1 and 184 (21.1%) had grade 2 RSN. Interobserver and intraobserver agreement for image interpretation showed weighted κ values of 0.798 and 0.888, respectively (n = 80). In multivariable analysis, hypertension grade (OR, 2.40; P <.001), hypertension duration (OR, 1.62; P <.001), cortical echo intensity (OR, 1.63; P <.001), and lower eGFR (OR, 0.625 per 10 mL/min/1.73 m² increase; 95% CI: 0.53–0.74; P <.001) were independently associated with RSN (AUC = 0.815). Renal damage was present in 5.2%, 8.0%, and 27.2% of patients with RSN grades 0, 1, and 2, respectively (P for trend <.001). Grade 2 RSN remained associated with renal damage after adjustment for age, sex, hypertension grade, and diabetes (OR, 8.77; 95% CI: 4.49–17.13; P <.001) and after further adjustment for eGFR as a continuous variable (OR, 2.88; 95% CI: 1.26–6.61; P = .012). In a sensitivity analysis restricted to the non-eGFR components of the endpoint and adjusted for continuous eGFR, the association was attenuated and no longer significant (OR, 1.55; P = .30). Among the 779 patients without threshold-defined renal damage, grade 2 RSN was present in 134 (17.2%), and eGFR declined progressively across RSN grades (medians, 98.8, 93.1, and 87.4 mL/min/1.73 m²; P <.001). Conclusions Ultrasound can detect and grade RSN, and RSN grade shows a dose–response association with renal damage in hypertensive adults. RSN was frequently present in patients whose eGFR and urinalysis remained within normal limits, suggesting that it may reflect structural change accompanying subclinical decline in renal function.