Gynecomastia, a very frequent disorder, is present in almost 40 % of y
oung men. In this population the investigations often fail to find any
aetiology, therefore defining idiopathic gynecomastia. The aim of thi
s work is to compare clinical and hormonal characteristics of 488 subj
ects with gynecomastia to 41 healthy controls. Their are many explanat
ions for the occurrence of idiopathic gynecomastia, including modifica
tion of hormonal balance, change of aromatase activity, or a receptor
anomaly. Our works demonstrate a significant decrease in mean testoste
ronemia, linked to a high prevalence of incipient hypogonadism in the
studied population, especially in patients with an history of testicul
ar disease.