Serum and breast duct fluid prolactin and estrogen levels in healthy Finnish and American women and patients with fibrocystic disease.

Nipple aspiration yielded measurable amounts of breast duct fluid for 27 of 42 (64%) healthy premenopausal Finnish women, 93 of 218 (43%) premenopausal American patients with fibrocystic disease, but only 24 of 92 (26%) healthy American premenopausal controls. When aspiration was successful, the average volumes obtained were larger for the normal Finnish women and, particularly, for the American fibrocystic disease patients compared with the American controls. The difference in secretion between the healthy Finnish and American women appeared to be related to a history of breast feeding, and its duration. While serum estrogen and prolactin concentrations were similar in the three groups, prolactin levels in breast fluids from the Finnish women were frequently higher than those in the American controls. A similar trend, which did not reach statistical significance, was observed in the 43 of 93 (46%) secretors with fibrocystic disease and cyclical mastalgia.