Normoprolactinemia in boys with marked gynecomastia

Pubertal gynecomastia normally occurs as a transient phenomenon of several months duration, whereas marked pubertal gynecomastia (more than 6 cm in diameter) may persist into aduldhood. In the present study the possible involvement of prolactin (PRL) secretion in the development of marked pubertal gynecomastia was investigated. The diurnal variations of PRL, luteinizing hormone (LH), follicle-stimulating hormone (FSH), as well as the basal values of testosterone (T) and estradiol (E₂) were determined in 5 pubertal boys with marked gynecomastia and in 5 age-matched controls. Mean age of all patients was 14.4 years. The pubertal development was classified as P 3–4.In comparison to controls, boys with marked gynecomastia revealed no differences in basal values of PRL, LH and FSH, as well as in peak values of all hormones during sleep. The response of PRL, LH and FSH to LHRH/TRH stimulation was normal for pubertal age in both groups. In comparison to controls, decreased mean plasma T levels (P<0.05) and slightly increased E₂ levels (P<0.05) were found in boys with marked gynecomastia. The E₂/T ratio was also higher in boys with gynecomastia (P<0.005).These data suggest that prolactin, a hormone which may be increased in galactorrhea, is not involved in the development of marked pubertal gynecomastia in boys. The above findings suggest that slightly elevated day-time E₂ levels may be involved in the development of female-appearing breasts in pubertal boys.