(422) Testosterone, Vitamin D and Bone Mineral Density in Men

Testosterone is known to enhance bone density by promoting trabecular bone formation but it still has not been confirmed as adjunctive therapy in osteopenia/osteoporosis even in hypogonadal men. On the other hand, vitamin D is associated with bone density and is used as a treatment modality for osteopenia/osteoporosis. However, there’s lack of study investigating the effect of both testosterone and vitamin D simultaneously on BMD (bone mineral density) in men. The authors tried to conduct a large scaled study to identify the relationship among testosterone, vitamin D and BMD in men. The present study is bi-centered, cross-sectional study from 2022 to 2024. Data were extracted from general population who visited our institutes for general check-up. Inclusion criteria should meet all of followings; 1) any men aged 20 years old or more, 2) patients having bone densitometry data, and 3) patients who tested blood testosterone, blood vitamin D, and bone densitometry. Patients were excluded if they had any one of followings; 1) hyperparathyroidism, 2) cancer related chemotherapy or radiotherapy, 3) prostate cancer with androgen deprivation therapy. Initial bone densitometry data were used in cases of duplication. SPSS (IBM Corp. Released 2019. IBM SPSS Statistics for Windows, Version 26.0. Armonk, NY: IBM Corp.) was used for the statistical analysis. Student t-test and Simple linear regression test were applied to univariate analysis. Multiple linear regression test including interaction effect and scatter plot with locally weighted scatterplot smoothing were used to identify the relationship among parameters. A p-value < 0.05 was considered significant. In total, 1888 persons were collected where 299 persons omitted blood testosterone test, 63 persons did not check blood vitamin D, 487 persons were undertaking chemotherapy and/or radiotherapy, or androgen deprivation therapy and 15 patents were diagnosed with hyperparathyroidism. Finally, 1024 patients were eligible. In univariate analysis, age and BMI (body mass index) were significantly related to BMD of both spine and hip. With respect to testosterone level, statistical significance was only observed in BMD of hip. When it comes to vitamin D, it has neither relationship with BMD of spine nor with BMD of hip (Figure 1). However, distributions of BMD of both spine and hip joint by age and BMI were influenced by both testosterone and vitamin D levels (Figure 2). Therefore, not only aging and BMI, but testosterone and vitamin D also were significantly related to BMD though vitamin D still related to BMD of hip alone in multiple regression analysis (Figure 3). It is because serum testosterone and vitamin D levels have interaction effect with age and BMI (Figure 2). Testosterone as well as vitamin D contribute significantly to BMD. Studies trying to elucidate the effect of testosterone replacement on BMD in hypogonadal men do not have to stick to osteoporosis. Instead, demographic parameters such as age and BMI should be well controlled before initiating clinical trials. No