Men who take androgen‑blocking drugs like the GnRH agonist triptorelin (often used to lower testosterone) lose bone density over several years. In this study, bone loss was about half a standard deviation at the spine and hip after roughly six years of treatment. People who also took bisphosphonate medicines did not see the same drop, suggesting those drugs can help protect bone.

Guidelines suggest treating men with paraphilic disorder with androgen-deprivation therapy (ADT). However, little evidence is available about the long-term impact on bone loss and how to manage this adverse event. The aim of this study is to assess the impact of ADT on bone mineral density (BMD) in men treated for paraphilic disorder with the androgen receptor blocker cyproterone acetate (CPA) and/or GnRH agonist triptoreline (GnRHa) and to evaluate the effect of treatment with bisphosphonates. Baseline and follow-up dual-energy X-ray absorptiometry scan (DXA-scan) data (lumbar and femoral T-scores) were retrospectively extracted from electronic medical files of paraphilic men who received CPA and/or GnRHa. A total of 53 patients with a mean age of 39.1 years (range 17.5-74.6) were included. Lumbar (-0.39 ± 0.17, Mean ± SEM, p = 0.046), femoral neck (-0.34 ± 0.09, p = 0.002) and total femur (-0.33 ± 0.12, p = 0.014) T-scores decreased significantly in the CPA-only group (n = 13) during a mean follow-up of 6.0 ± 5.3 years. In the GnRHa group (n = 29), T-scores at all sites decreased significantly over 6.6 ± 4.4 years (lumbar: -0.55 ± 0.12, p < 0.001, femoral neck: -0.53 ± 0.09, total femur: -0.44 ± 0.09, p < 0.001). In the group, who received bisphosphonates (n = 11), no significant T-score change was observed (lumbar: -0.25 ± 0.14, p = 0.106, femoral neck -0.15 ± 0.17, p = 0.402, total femur -0.25 ± 0.14, p = 0.106) during 5.0 ± 2.8 years of follow-up. Following a mean duration of 6 years of ADT, we observed a significant decline in BMD of approximately half a standard deviation in T-score at lumbar and femoral site. Although the number of patients who received bisphosphonates was limited, this treatment seems to have a positive stabilizing effect on bone density.