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Abstract Background Osteoporosis is a common condition that weakens bone and increases fracture risk. In clinical practice, bone mineral density (BMD) measured by dual-energy X-ray absorptiometry (DXA) is widely used for diagnosis, but it does not fully reflect bone structural properties. Geometric parameters of the proximal femur derived from DXA may provide additional biomechanical information. However, existing studies were often limited by small cohorts, single-region analyses, and a lack of clinically applicable reference thresholds. This study aimed to investigate the diagnostic potential of multi-regional femoral geometric parameters obtained from DXA in a large population. Methods A total of 811 adults aged ≥ 50 years (mean 65 ± 8.4 years; 54.9% women) underwent hip DXA using a Hologic Horizon Wi system. Based on femoral neck (FN) T-scores, participants were categorized into three groups: normal bone mass ( n = 243), osteopenia ( n = 428), and osteoporosis ( n = 140). Geometric parameters—including cross-sectional area (CSA), cross-sectional moment of inertia (CSMI), cortical thickness (Ct.Th), section modulus (Z), and buckling ratio (BR)—were derived from hip structural analysis (HSA) at the narrow neck (NN), intertrochanteric (IT), and femoral shaft (FS) regions. Statistical assessments included inter- and intra-rater consistency testing, one-way ANOVA and Kruskal–Wallis test, Pearson correlation analysis, multiple linear regression, and receiver operating characteristic (ROC) curve analysis. Results All geometric parameters differed significantly among bone status groups ( p < 0.001). CSA, CSMI, Z, and Ct.Th progressively declined with worsening BMD, whereas BR increased. Regionally, CSA, CSMI, and Z were greatest at IT, Ct.Th at FS, and BR at NN. NN-Ct.Th showed the strongest correlation with femoral neck BMD ( r = 0.83) and emerged as a robust independent predictor in regression analysis. ROC analysis demonstrated high discriminative performance of NN-Ct.Th (AUC = 0.96 for low bone mass; AUC = 0.968 for osteoporosis) within the FN-BMD-defined framework. Notably, cohort-specific reference thresholds for NN-Ct.Th (< 0.165 cm for low bone mass and < 0.135 cm for osteoporosis) were identified, with minor sex-related variation. Conclusions In this large DXA-based cohort, NN-Ct.Th showed a strong correlation with bone mass status and may serve as a complementary parameter within routine DXA interpretation, particularly in the BMD diagnostic gray zone (− 2.5 < T-score < − 1.0). The proposed thresholds represent preliminary, device-specific reference values that require external validation and assessment against fracture outcomes before broader clinical implementation.