Effects of Sympathetic Activity on Human Skeletal Homeostasis: Clinical Evidence from Pheochromocytoma

Prevalence and Predictors of Osteoporosis/BMD Below Expected Range for Age in Pheochromocytoma/Paraganglioma and BMD, TBS Change Post-Operatively: A Prospective Cohort Study

Context

Pheochromocytomas/paragangliomas (PPGLs) have recently been shown to be associated with lower bone mineral density (BMD) and trabecular bone score as compared to healthy controls suggesting low bone mineral concentration and disrupted bone microarchitecture. There is paucity of data on prevalence and clinical predictors of low BMD/osteoporosis in PPGL from India and the extent of change in BMD post-operatively.

Aims

This study aimed to find prevalence of low BMD/osteoporosis and trabecular bone score (TBS)-adjusted FRAX score in subjects with PPGL and to see the post-operative change in BMD and TBS at follow-up.

Material and Methods

32 consecutively diagnosed adult cases with PPGL were enrolled. Although the provisional diagnosis of PPGL was made based on imaging consistent with PPGL supported by biochemical evidence of catecholamine excess, its confirmation was made histopathologically before final analysis.

Results

We found significantly low average BMD T-score/Z-score at spine, hip or wrist. Osteoporosis was evident in 87.5% of subjects (nine of 11 post-menopausal women or men >50 years of age) and BMD below the expected range for age in 42.9% of subjects (nine of 21 pre-menopausal women or men <50 years of age) by International Society for Clinical Densitometry criteria.

Conclusions

87% of older subjects with PPGL had osteoporosis while 43% of younger subjects had BMD below expected range for age (Z-score ≤-2.0), more at lumbar spine than at hip. Decreased body weight was associated with osteoporosis in older or Z-score ≤-2.0 in younger subjects. There was no significant change in BMD and TBS scores at a median of four months post-operatively.

Regulation of bone metabolism mediated by β-adrenergic receptor and its clinical application

Recent studies have confirmed that β-adrenergic receptors (β-ARs) are expressed on the surface of osteoblasts and osteoclasts, and that the sympathetic nervous system can regulate bone metabolism by activating them. β-AR blockers (BBs) are commonly used in the treatment of cardiovascular diseases in the elderly. It is important to investigate whether BBs have a beneficial effect on bone metabolism in the treatment of cardiovascular diseases, so as to expand their clinical application. This article reviews the effects of BB on bone metabolism and the progress of clinical research.