A serum metanephrines test measures the metabolites of epinephrine and norepinephrine. These catecholamines are produced in excess by an adrenal or extra-adrenal tumor seen in pheochromocytoma. The classic triad of symptoms of pheochromocytoma are hypertension, sweating, and headache; approximately 30% of patients report significant anxiety and panic (Table 15-7). This type of tumor is rare, with an annual incidence of only 2 to 8 cases per 1 million individuals. Among people with hypertension, the annual incidence is 0.1% to 1.0%, and for those with an adrenal mass, the annual incidence is 5% (Table 26,8). Autopsy studies suggest that up to 50% of pheochromocytomas are undiagnosed.8 Left untreated, pheochromocytoma can result in hypertensive crisis, arrhythmia, myocardial infarction, multisystem organ failure, and premature death.7Table 36,7 highlights some causes of false-positive serum on metanephrines testing.
EVALUATION Metanephrines testing
Mr. P has what appears to be treatment-resistant hypertension, accompanied by the classic symptoms observed in most patients with pheochromocytoma. Because Mr. P is participating in the PHP 6 days per week for 6 hours each day, visiting his PCP would be inconvenient, so the treatment team orders the serum metanephrines test. If a positive result is found, Mr. P will be referred to his PCP for further assessment and follow-up care with endocrinology.
TREATMENT Pharmacotherapy to target anxiety and panic
Next, the treatment team establishes a safety plan for Mr. P, and restarts paroxetine, 20 mg/d, to target his depressed and anxious mood. Alprazolam, 0.5 mg twice daily, is started to target anxious mood and panic symptoms, and to allow time for the anxiolytic properties of the paroxetine to become fully effective. The alprazolam will be tapered and stopped after 2 weeks. Mr. P is started on hydroxyzine, 1 to 2 25-mg tablets 2 to 3 times daily as needed for anxious mood and panic symptoms.
The serum metanephrines test results are equivocal, with a slight elevation of both epinephrine and norepinephrine that is too low to confirm a diagnosis of pheochromocytoma but too elevated to exclude it (Table 49). With Mr. P’s consent, the treatment team contacts his PCP and convey the results of this test. Mr. P schedules an appointment with his PCP for the following week for further assessment and confirmatory pheochromocytoma testing.
After 1 week, Mr. P remains anxious, with a slight reduction in panic attacks from multiple attacks each day to 3 or 4 attacks per week. The team considers adding an additional anxiolytic agent.
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