Increased plasma dopamine in patients presenting with the pseudopheochromocytoma quandary: retrospective analysis of 10 years' experience

Abstract

Objectives: A retrospective analysis was made to determine alternative diagnoses in patients with predominantly hypertensive episodes who were suspected of having pheochromocytoma but in whom this diagnosis was eliminated.

Design: Analysis of a random university hospital population referred over a period of 10 years.

Methods: Episodic clinical presentations of pheochromocytoma symptoms combined with a comparison of baseline and episodic radioenzymatically determined levels of plasma free norepinephrine and epinephrine were examined, together with prospective levels of plasma free and sulfated dopamine.

Results: Out of 63 patients presenting with episodes of palpitations, headaches, flushing, sweating and hyperventilation (associated with hypertension in 49 patients, with hypotension in six patients and with alternating hyper- and hypotension in eight patients), 14 were diagnosed as having idiopathic hypovolemia, nine as having mastocytosis, nine as having an adrenal tumor, four as having neurogenic hypertension and one each with cocaine abuse and reninoma. Both baseline and symptomatic levels of plasma free norepinephrine and epinephrine remained within physiological limits (exceeding them moderately in baroreceptor dysfunction only), but all subgroups had a mean episodic increase over baseline in plasma dopamine sulfate (mean+/-SEM 16.7+/-5.9 to 53.2+/-19 pmol/ml; P < 0.02), unlike free dopamine.

Conclusions: Patients whose symptoms imitated pheochromocytoma in hemodynamic instability and frequent flushing formed a heterogeneous group, with plasma norepinephrine and epinephrine usually within physiological limits but an overall mean threefold increase in dopamine sulfate concentrations. With the various diagnoses of idiopathic hypovolemia, mastocytosis, neurogenic, secondary hypertension and cocaine abuse eliminated as a cause of pheochromocytoma-like symptoms, at least half of these patients still had unexplained, predominantly emotionally or proprioreceptive stimulation-provoked, bouts of hypertension. Sympathetic arousal dominated by an increase in dopamine sulfate without a corresponding increase in free norepinephrine, epinephrine and dopamine may be attributed to a number of neurogenic, adaptive or autocrine-paracrine dopamine release mechanisms.