Pheochromocytomas and paragangliomas (PPGLs) may be an important cause of secondary osteoporosis, as these tumors were found to be associated with lower bone mineral density (BMD) at trabecular bone and increased risk for vertebral fractures, according to study results published in Bone.

Previous studies have reported that PPGLs are associated with low BMD, but limited data are available on the association between these catecholamine-producing neuroendocrine tumors and the risk for osteoporotic fracture or the effect of surgical removal of these tumors on BMD. The goal of the current study was to explore the association between PPGL and vertebral fractures, as well as the effect of treatment on BMD.

The retrospective cross-sectional study included patients with pheochromocytoma or paraganglioma treated at Kyushu University Hospital in Japan. Of 443 patients with adrenal tumors, 114 were found to have PPGL, and after exclusion, the cohort included 49 patients with PPGL and 61 patients with nonfunctional adrenal tumor with available radiographs. Follow-up data for BMD were available for 23 patients with PPGL.

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The researchers compared the prevalence of vertebral fracture and clinical characteristics among patients with nonfunctional adrenal tumor and those with PPGL. Furthermore, in the group of patients with PPGL, BMD was evaluated at baseline and after surgical removal of the tumor.

Among patients with PPGL, the prevalence of vertebral fracture was significantly higher compared with that in patients with nonfunctional adrenal tumors (43% vs 16%, respectively; P =.002).

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All vertebral fractures that occurred in patients with nonfunctional adrenal tumors were morphometric vertebral fractures, whereas in the group of patients with PPGL, there was 1 case of a clinical vertebral fracture.

Regardless of age and sex, diagnosis of PPGL was associated with a >4-fold increase in the risk for vertebral fracture (odds ratio, 4.47; 95% CI, 1.76-11.3; P =.001). This association remained significant after adjustment for various known risk factors for vertebral fractures.

After surgical removal of the neuroendocrine tumor, BMD at the lumbar spine improved by 3.8% (baseline: 0.855±0.198 g/cm2; after surgery: 0.888±0.169 g/cm2; P =.026). In a similar fashion, BMD z score at the lumbar spine also improved (baseline: -0.5±1.0; after surgery: -0.2±0.9; P =.005). There was no change in BMD or BMD z score at the femoral neck.

The study had several limitations, including the retrospective design, small sample size within a single center, lack of matching, and limitations secondary to choosing patients with adrenal tumors as controls, as these tumors may secrete small amounts of adrenal hormones.

“PPGLs are associated with [vertebral fracture]. Surgical resection contributes to the improvement of BMD in patients with PPGLs. Our data provide evidence that PPGLs could be an emerging cause of secondary osteoporosis,” concluded the researchers.

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Yokomoto-Umakoshi M, Umakoshi H, Fukumoto T, et al. Pheochromocytoma and paraganglioma: an emerging cause of secondary osteoporosis. Bone. 2020;133:115221.