Source of plasma adrenomedullin in a patient with pheochromocytoma receiving hemodialysis

Abstract

A 45-year-old man on long-term hemodialysis (HD) was incidentally discovered to have a pheochromocytoma and underwent successful resection. This patient was normotensive, and had no symptoms suggesting pheochromocytoma. The plasma concentrations of total adrenomedullin (AM-T) and mature AM (AM-m) were higher than those in normal controls. To elucidate the source of AM, we measured plasma AM levels by immunoradiometric assay before and 3 weeks after surgery in addition to plasma adrenaline, noradrenaline and dopamine. AM expression was also assessed by immunoblot and immunohistochemical analyses on normal adrenal and tumor tissues. After surgery, elevated plasma adrenaline levels returned to the normal range; however, the levels of AM-T and AM-m remained almost the same as the preoperative values. Furthermore, although AM was expressed in both normal adrenal and tumor tissues, the AM expression level was less in tumor. In this case, it was suggested that elevation in plasma AM level might be a factor associated with normotensive blood pressure; however, adrenal pheochromocytoma was not a major source of circulating AM. To our knowledge, this is the first case of pheochromocytoma in patient with HD associated with AM in the literature.