Besides the size growth of breast tissue, there may also only be increased fat present. If that is the case, this indicates a “false gynecomastia (pseudogynecomastia, lipomastia). Most common, however, is a mixed form, where there is breast tissue and increased fat.
Most often true gynecomastia occurs in puberty (65%). During puberty, a young man’s hormone production in the testes begins. In addition to testosterone, the precursor hormon of estrogen -estradiol- is also produced. Often the estradiol raises faster than the testosterone concentration, thereby increasing existing breast tissue and, finally, a gynecomastia. After completing puberty, the breast usually reduces back to normal size although this may sometimes fail, despite normal hormone levels.
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