Endocrine Abstracts

Background: Urinary metanephrine (MN) and normetanephrine (NMN) are used to detect recurrence of pheochromocytoma during post-operative period. Currently, reference ranges of urinary MN and NMN obtained from healthy individuals are applied to subjects with adrenalectomy. However, studies regarding the property of using reference ranges from healthy subjects in pheochromocytoma subjects with adrenalectomy are limited.

Aim: To compare urinary MN and NMN concentrations in patients after unilateral adrenalectomy to concentrations in healthy subjects.

Methods: A single-center retrospective study was conducted in pheochromocytoma patients confirmed with pathology. Eighty-two patients underwent unilateral adrenalectomy between February 2004 and June 2014 and had no evidence of recurrence during follow-up period. Urinary MN and NMN were checked before and after surgery with 3- or 6 month-intervals.

Results: Urinary MN concentration after unilateral adrenalectomy was lower than control group (70.0 μg/day vs 92.0 μg/day, P<0.001), whereas urinary NMN was not different (220.9 μg/day vs 232.0 μg/day). According to post-operative period, urinary NMN determined in immediate post-operative period (whithin 1 month after surgery) was higher than the concentration in the period between 12 and 36 months (287.3 μg/day vs 204.0 μg/day, P<0.01). Urinary MN in male subjects was higher compared to the concentration in female subjects (81.0 μg/day vs 64.8 μg/day, P<0.01).

Conclusions: Urinary MN concentration in pheochromocytoma patients after unilateral adrenalectomy was lower than the concentration in control group. Different reference ranges of urinary MN are needed for post-operative pheochromocytoma patients. Urinary NMN was not different in both groups, however tendency that the concentration was higher in immediate post-operative period was observed.