Physiologic concentrations of dopamine fail to suppress prolactin secretion in patients with idiopathic hyperprolactinemia or prolactinomas.
Several investigators have suggested that normal responsiveness to dopamine is exhibited by pituitary lactotrophs in patients with idiopathic hyperprolactinemia and prolactinomas. These studies, however, have employed dopamine infusion rates that produced supraphysiologic serum dopamine concentrations. In order to further examine this issue, we infused graded doses of dopamine to normal men and women as well as to patients with idiopathic hyperprolactinemia and prolactinomas. Dopamine infusion rates as low as 0.004 micrograms/kg/min, which were associated with physiologic serum dopamine levels, produced significant (p less than 0.01) suppression of prolactin in normal women and in normal males (p less than 0.05). In contrast, a 10-fold increase in the dopamine infusion rate, 0.04 micrograms/kg/min, was required in the hyperprolactinemic subjects to produce prolactin suppression similar to that found in the control subjects. Hence, prolactin secretion in both tumors and other hyperprolactinemic states is associated with a resistance to suppression by dopamine.
D000293:Adolescent; D000328:Adult; D004298:Dopamine / Q000097:blood / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D007263:Infusions, Parenteral; D008297:Male; D008875:Middle Aged; D010911:Pituitary Neoplasms / Q000097:blood / Q000378:metabolism* / Q000503:physiopathology; D011388:Prolactin / Q000097:blood* / Q000378:metabolism; D012727:Sex Characteristics; D013997:Time Factors
D011388:Prolactin; D004298:Dopamine