MON-204 Pheochromocytoma and Paraganglioma: An Emerging Cause of Secondary Osteoporosis

Context: Many endocrine diseases are known to cause secondary osteoporosis, which is potentially reversible by treatment of the underlying disease itself. Pheochromocytoma (PHEO) and paraganglioma (PGL) (PHEO and PGL: PPGLs) are the rare catecholamine-producing neuroendocrine tumors, which are associated with low bone mineral density (BMD). However, PPGLs have not been recognized as a cause of secondary osteoporosis. Indeed, even the prevalence of osteoporotic fracture in patients with PPGLs is currently unknown. Furthermore, whether surgical resection contributes to the improvement of BMD has never been addressed. Objective: This study was designed to evaluate 1) whether PPGLs increase the risk of vertebral fracture (VF), which is the most common type of osteoporotic fracture and 2) whether surgical resection of PPGLs contributes to the improvement of BMD. Design and Settings: A retrospective cross-sectional study in a single referral center. Participants: Among 443 patients with adrenal tumor (AT), we included 62 patients with histologically confirmed PPGLs and 61 patients with non-functional AT. Intervention: The prevalence of VF was examined in 49 out of 62 patients with PPGLs and 61 patients with non-functional AT. In 23 out of 62 patients with PPGLs, BMD was evaluated at baseline and after surgery. Results: PPGLs had a higher prevalence of VF (43% [21/49]) than non-functional AT (16% [10/61]; p = 0.002). PPGLs were an independent risk factor for VF after adjusting for age and sex (odds ratio, 4.47; 95% confidence interval, 1.76–11.3; p = 0.001). In PPGLs, BMD expressed as Z score at the lumbar spine was significantly improved at follow-up (before -0.5±1.0, after -0.2±0.9; p = 0.005). Conclusion: This study demonstrates that PPGLs are an independent risk factor for VF and that their surgical resection contributes to the improvement of BMD in the trabecular bone. These observations support the notion that PPGLs are an emerging cause of secondary osteoporosis.