[Plasma prolactin levels and pubertal gynecomastia].

Twenty-three boys with pubertal gynecomastia had higher mean levels of prolactin than boys of similar development but without gynecomastia (10.1 vs. 6.2 ng/ml). In girls of comparable pubertal staging prolactin level was 12.3 ng/ml. In boys no hyperprolactinemia was found, not even after stimulation with TRH, prolactin levels were not elevated in two boys with secreting mammary glands. Therapy with bromocriptine stopped the secretion. During therapy, prolactin levels could not be raised by stimulation. The results contradict the hypothesis that prolactin is involved in the development of gynecomastia.