Serum Levels of Prolactin in Basal Conditions and after Administration of 2-Bromo-5α-Ergocryptine in Normal and Galactorrheic Subjects

Abstract

Serum levels of prolactin were measured basally and after the oral administration of 2.5 mg of 2-bromo-5α-ergocryptine to healthy male (n = 4) and female (n = 5) subjects; to women with spontaneous galactorrhea and normal, biphasic cycles (n = 3); to galactorrheic women with spontaneous bleeding but no indirect signs of ovulation (n = 9); to galactorrheic-amenorrheic women with no evidence of pituitary adenoma (n = 19); and to galactorrheic-amenorrheic women with roentgenologic signs of pituitary adenoma (n = 4). The drug was given between 8:00 and 9:00 A.M.; blood samples were obtained before and 60, 120, 180, and 240 minutes and 24 hours after the administration of 2-bromo-5α-ergocryptine. Serum levels of prolactin were measured by radioimmunoassay with a double-antibody technique. The mean basal prolactin level in normal men was 12.5 ± 1.0 ng/ml; in normal women (7th to 9th days of the cycle) it was 16.2 ± 4.0 ng/ml. After drug administration serum levels of prolactin decreased progressively and systematically; minimal values were found at 180 to 240 minutes. The lowest maximal percentage of inhibition in normal subjects was 56%. Basal prolactin levels in galactorrheic women tended to be higher in relation to the severity of the pathophysiologic involvement. The highest levels were found in patients with demonstrable tumors. The drug-induced percentage reduction of these prolactin levels was lower in galactorrheic women than in normal women; paradoxical increases in prolactin levels occurred in some cases. The wide variability of the results obtained in the galactorrheic groups would restrict the practical application of this testing procedure.