Prolactin Response to the Dopamine Antagonists Sulpiride and Domperidone

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Abstract
The PRL response to the dopamine antagonists sulpiride (100 mg i.m.) or domperidone (2 or 8 mg i.v.) was evaluated in healthy controls and in 148 patients with different hyperprolactinemic disorders (50 with idiopathic hyperprolactinemia, 58 with microprolactinoma, 19 with macroprolactinoma, 2 with empty sella, 8 with acromegaly, 7 with organic lesions of the hypothalamus, and 4 with idiopathic hypopituitarism of presumed hypothalamic origin). Mean PRL response to both drugs was significantly lower in all groups of patients than in controls, and significantly higher in subjects with idiopathic hyperprolactinemia than in those with pituitary adenomas or hypothalamic disease. Absent or impaired PRL responses were found in 38 % of idiopathic patients, in 91.5 % of microprolactinomas and in all of the patients with either macroprolactinoma, acromegaly, or hypothalamic disorders. Since the PRL response to dopamine antagonists depends on the presence of an endogenous dopaminergic tone, it is suggested that these figures reflect the incidence of major dopamine deficiency at pituitary lactotrophs in different hyperprolactinemic states. These data suggest that the pathophysiology of hyperprolactinemia in many patients with idiopathic disease is different from that of microprolactinoma. However, the finding of a normal PRL response to sulpiride in some subjects with radiologically or surgically proven microprolactinoma indicates that this test has no diagnostic value in the individual case.