MON-079 - A Rare Case of TMEM127 Pheochromocytoma with Co-Existing Hyperthyroidism

Pheochromocytoma and hyperthyroidism are separate entities with similar clinical features due to shared enhanced sympathetic activity. The overlap of symptoms such as tremor, anxiety, and diaphoresis can be a diagnostic dilemma; particularly if a patient presents with abnormal biochemical testing for one diagnosis before testing for the other. We describe a case of pheochromocytoma discovered after initial presentation of hyperthyroidism.
39-year-old male presented for evaluation of panic attacks, palpitations, tremors, and flushing. His initial TSH was suppressed at 0.319 uIU/mL (0.358-3.74) with a free T4 of 1.13 ng/dL (0.89-1.76). Due to worsening panic episodes, metanephrines were completed which showed elevated plasma metanephrines at 89 pg/ml (This case exemplifies the rare possibility of co-existing thyroid dysfunction and pheochromocytoma. Additionally, we note the full spectrum of function of TMEM127 as it relates to syndromic features is yet to be determined. We recommend an increased suspicion and diagnostic testing consideration for those patients with severe adrenergic activity, and particularly those with persistent symptoms after initial treatment.

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