Pheochromocytoma and paraganglioma with negative results for urinary metanephrines show higher risks for metastatic diseases.

Our findings demonstrate that PPGL patients with negative results for urinary metanephrines are associated with extra-adrenal lesions, metastatic disease, and negative MIBG findings. This suggests that PPGL patients with negative results for urinary metanephrines have a greater need for systemic whole-body imaging other than MIBG scintigraphy and close follow-up to monitor for metastasis than do patients with PPGL overtly producing excessive catecholamine.