Six patients being evaluated for phaeochromocytoma had misleading investigative findings: all initially had raised urinary catecholamine levels, and five had adrenal masses on imaging studies. Adrenalectomy in these five patients revealed only one pathologically confirmed phaeochromocytoma. Tricyclic antidepressant use produced misleading elevations in urinary catecholamine levels in three patients. 24-hour urine studies should be performed at least twice, after eliminating confounding factors (stressors, medications).
The details of six patients treated in the period April 1999 – October 2003 by members of the Section of Endocrine Surgery of the Royal Australasian College of Surgeons are outlined in Box 1. In all patients, clinical suspicion of phaeochromocytoma was raised by the presence of hypertension, paroxysmal symptoms, or both. Twenty-four-hour urinary catecholamine levels were found to be elevated, although in Patients 1–5 these abnormalities were confined to one or two analytes only. In all except Patient 2, adrenal lesions were discovered on imaging, with large haemorrhagic masses detected in patients with an acute presentation (Patients 5 and 6). Patients with abnormalities on computed tomography (CT) underwent surgery. In Patients 1, 3, and 4, the excised tissues were found to be pathologically normal or to show mild enlargement (benign). In Patients 5 and 6, blood clot and necrotic tissue comprised the bulk of the specimens (Box 2), with a phaeochromocytoma discovered in the latter patient. Of note, Patients 1–3 were receiving tricyclic antidepressants for non-standard uses that did not include the treatment of major depression.
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