Utility of plasma free metanephrines in diagnosis of factitious pheochromocytoma

Objective: To report a case of epinephrine-induced factitious pheochromocytoma in a young woman with a past medical history of Conn's syndrome. Methods: We present a case report with clinical and laboratory details, review related reports in the literature, and demonstrate the usefulness of plasma free metanephrine levels in facilitating the diagnosis of factitious pheochromocytoma. Results: A 34-year-old woman was admitted to our hospital for confirmation and localization of an occult pheochromocytoma. After thorough investigation, we discovered that the patient was surreptitiously injecting epinephrine in order to induce symptoms and signs consistent with a pheochromocytoma. Analysis of the patient's biochemical profile during and between her catecholaminergic crises revealed plasma epinephrine and free metanephrine levels that would be highly unusual for a patient with a pheochromocytoma. Conclusion: This case illustrates the utility of implementing the ratio of plasma epinephrine to free metanephrine levels in distinguishing factitious from organic pheochromocytoma.