Bone resorption is increased in pheochromocytoma patients and normalizes following adrenalectomy.

CONTEXT: The sympathetic nervous system (SNS) controls bone turnover in rodents, but it is uncertain whether a similar role for the SNS exists in humans. Pheochromocytomas are catecholamine-producing neuroendocrine tumors. Because catecholamines are the neurotransmitters of the SNS, we hypothesized that pheochromocytoma patients have increased bone turnover.
OBJECTIVE: Our objective was to compare bone turnover in pheochromocytoma patients and controls. DESIGN AND
SETTING: This retrospective case-control study was performed at the Endocrine Department of the Academic Medical Center of the University of Amsterdam in The Netherlands from 2007 until 2011. PATIENTS: All patients were screened for pheochromocytoma. Cases (n = 21) were identified by 24-h urinary excretion of fractionated metanephrines above the institutional reference value and confirmed by histology after adrenalectomy. All patients screened and diagnosed as not having pheochromocytoma served as controls (n = 126). MAIN OUTCOME MEASURE: The difference in bone turnover markers C-terminal cross-linking telopeptides of collagen type I (CTx) and procollagen type 1 N propeptide (P1NP) between cases and controls was the main outcome measure.
RESULTS: CTx concentrations were higher in cases [343 ng/liter; interquartile range (IQR), 295 ng/liter] than in controls (232 ng/liter; IQR, 168 ng/liter; P < 0.001) and decreased after adrenalectomy [before, 365 ng/liter (IQR, 450 ng/liter); after, 290 ng/liter (IQR, 241 ng/liter); P = 0.044]. The effect remained after adjustment for possible confounders. P1NP concentrations did not differ.
CONCLUSIONS: This study shows that pheochromocytoma patients have increased bone resorption, which normalizes after adrenalectomy. This finding supports the concept of regulation of bone remodeling by the SNS in humans.