Composition of breast fluid of a man with galactorrhea and hyperprolactinaemia.

It has been previously reported that men with and without known disease can produce milk, but no studies to date have demonstrated that their secretion contains milk constituents produced specifically by the breast. The present study shows the presence of lactose, alpha-lactalbumin, and lactoferrin in the breast secretion of a 27-yr-old male who had galactorrhea associated with hyperprolactinaemia. The concentrations of lactose, proteins, and electrolytes in the breast secretion of this man are within the range of colostrum and milk obtained from normal lactating women.