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Adrenal incidentaloma, borderline elevations of urine or plasma metanephrine levels, and the "subclinical" pheochromocytoma.

OBJECTIVE
To assess the risk of pheochromocytoma in patients with borderline-elevated urine or plasma metanephrine levels.


DESIGN
Retrospective review.


SETTING
University tertiary care center.


PATIENTS
Forty-two consecutive patients with adrenal incidentalomas (defined as adrenal tumors identified during routine imaging for another condition) who were treated at the UCSF (University of California, San Francisco) Medical Center between January 1, 1995, and July 31, 2005. Patients with genetic syndromes were excluded.


INTERVENTION
Laparoscopic adrenalectomy for adrenal incidentaloma based on size criteria and preoperative hormonal test results.


MAIN OUTCOMES MEASURES
Urine or plasma metanephrine and catecholamine levels, tumor size, and presence of pheochromocytoma.


RESULTS
Of 42 patients, 14 (33%) had a pheochromocytoma (11 of whom had clear-cut elevations in urine or plasma metanephrine levels defined as greater than 2 times the upper limit of normal) and 28 did not. Ten of the 42 patients (24%) had borderline elevations in urine or plasma metanephrine levels (defined as 1-2 times the upper limit of normal), 3 of whom had a pheochromocytoma (30%). Of patients with borderline elevations, mean +/- SD tumor size was 5.4 +/- 3.1 and 4.8 +/- 1.9 cm for patients with and without pheochromocytoma, respectively (P = .37). In these 10 patients, no clinical factors (age, sex, hypertension, presence of symptoms, number of antihypertensive medications, preoperative hemodynamics, or size of tumor on computed tomographic scan) allowed differentiation between those with and without pheochromocytoma.


CONCLUSIONS
Thirty percent of patients with adrenal incidentaloma and borderline-elevated urine or plasma metanephrine levels had a pheochromocytoma. Clinical factors cannot distinguish between those with and without pheochromocytoma. In this group of patients, we advocate either routine alpha-blockade preoperatively or further diagnostic tests to better characterize the tumor.