A Case of Pseudopheochromocytoma Associated with Clozapine Therapy

Background: An elevated plasma noradrenaline level is a consistent clinical effect of clozapine, which is due to its potent effect on α2-adrenergic receptors. Clozapine, a tricyclic dibenzodiazepine derivative, is used to treat refractory schizophrenia. In this report we present a case of pseudopheochromocytoma in a schizophrenic patient treated with clozapine. Case: A 55-year-old female diagnosed with schizophrenia referred from psychiatry clinic to endocrinology clinic detected with bilateral adrenal masses. She was hypertensive and she used nifedipine. Urine catecholamines, especially normetanephrine, were extremely elevated; however, she did not have any pheochromocytoma-related symptoms. Adrenal imaging was not compatible with pheochromocytoma. Following psychiatric consultation, clozapine was withdrawn for 1 week, and then 24-h urine catecholamineswere normal. Metaiodobenzylguanidine (MIBG) scan was normal. Conclusion: Given the potentially significant morbidity associated with paranoid schizophrenia, especially in undiagnosed cases, we recommend timely urinary catecholamine screening in patients that develop hypertension or other typical symptoms following the use of clozapine.