Abstract: Objective To analyze the diagnostic value and correlation of 25-hydroxyvitamin D ［25-(OH)D］, D-dimer (DD), and procollagen Type Ⅰ N-terminal propeptide (PINP) in postmenopausal osteoporosis (PMOP) in postmenopausal women. 
Methods A total of 255 postmenopausal women who underwent physical examinations in the Physical Examination Center of Shanghai Health and Medical Center from January 2022 to December 2024 were collected as research subjects and divided into three groups according to the lowest T value of bone mineral density (BMD): normal group (T value≥-1.0), osteopenia group (-2.5＜T value＜-1. 0), and osteoporosis group (T value≤-2.5). The serum 25-(OH)D, DD and PINP concentrations were compared among the three groups. The correlation between serum 25-(OH)D, DD and PINP concentrations and L1-4 BMD, femoral neck BMD and left hip BMD in postmenopausal women was analyzed by Pearson correlation analysis. The diagnostic efficacy of serum 25-(OH)D, DD and PINP in PMOP was analyzed by receiver operating characteristic (ROC) curve. 
Results The age ［(59.98±3.49)years］ and menopause duration ［(7.28±2.39) years］ of the osteoporosis group were significantly higher than those of the normal group ［(52.76±3.87) years, (2.90±2.57) years］ and the osteopenia group ［(55.02±4.18) years, (4.52±2.99) years］. The total BMD of L1-4 ［(0.730±0.064）g/cm2］, femoral neck BMD［(0.680±0.057)g/cm2］, and the total BMD of the left hip［(0.868±0.059)g/cm2］ were significantly lower in the osteoporosis group compared with the normal group (P＜0.05). The osteoporosis group had significantly higher age and menopause duration compared with the osteopenia group, and significantly lower total BMD of L1-4, femoral neck BMD, and total BMD of the left hip compared with the osteopenia group (P＜0.05). The 25-(OH)D level ［(17.70±7.28)μg/L］ in the osteoporosis group was significantly lower than that in the osteopenia group ［(21.15±4.88 )μg/L］ and the normal group ［(25.43±4.15)μg/L］, while DD ［(0.52±0.16)mg/L］ and PINP ［(67.94±15.76)μg/L］ were significantly higher than those in the other two groups (P＜0.05). The 25-(OH)D concentration in the osteoporosis group was significantly lower than that in the osteopenia group, while the DD and PINP concentrations were significantly higher than those in the osteopenia group (P＜0.05). Pearson correlation analysis revealed that serum 25-(OH)D concentrations in postmenopausal women were positively correlated with total BMD of L1-4, femoral neck BMD, and total BMD of the left hip (P＜0.001), while serum DD and PINP concentrations were negatively correlated with total BMD of L1-4, femoral neck BMD, and total BMD of the left hip (P＜0.001). The are under the ROC curve (AUC) values of 25-(OH)D, DD, and PINP alone and in combination for the diagnosis were 0.765, 0.852, 0.712, and 0.968, respectively, and serum 25-(OH)D, DD, and PINP all had certain diagnostic value in diagnosing PMOP. The combined diagnosis had a sensitivity of 96.7% and specificity of 88.2%, and the combined diagnostic value was significantly better than the single diagnosis of each serum indicator (Z=7.036, 12.927, 5.219, 43.446, all P＜0.05). 
Conclusion Serum 25-(OH)D, DD, and PINP levels are closely related to BMD in different body parts, and have certain diagnostic value in the diagnosis of PMOP, and the combined diagnostic value is higher. 

Key words: osteoporosis, postmenopause, calcifediol, D-dimer