This paper documents an unexpected rise in plasma aldosterone concentration (PAC) to the furosemide-upright test despite a decrease in adrenocorticotropin (ACTH) by dexamethasone, and an unresponsiveness in plasma renin activity to this stimulus in a patient with aldosterone producing adenoma. Furthermore, this patient showed an appropriate response in PAC to a rapid ACTH test, and an insensitivity in PAC to angiotensin-II (Ang-II) infusion. Other factor(s) besides ACTH or Ang-II may play a role in the plasma aldosterone response to ambulation after intravenous furosemide administration in patients with primary aldosteronism.