Breast enlargement among teenage boys has a significant detrimental effect on their mental and emotional health, a new study has found.

Male breast enlargement is known as gynaecomastia. It can range from a small mass of tissue behind the nipple to a much bigger enlargement, with the breast assuming a feminine appearance.

It tends to peak at three times during a male's life - when he is newborn, when he is a teenager and during middle-age. It can be caused by a range of things, from obesity to disorders of the thyroid gland.

According to doctors in the US, even mild gynaecomastia can have adverse psychological effects in teenagers. They followed the progress of almost 50 healthy teenagers, with an average age of 16. All were being assessed for male breast enlargement. These were then compared to a group of teenagers who did not have the condition.

Almost two in three of the gynaecomastia group had mild to moderate breast enlargement. The majority of these were overweight or obese.

The quality of life of all of the participants was assessed and this revealed a number of problems for those with breast enlargement. They tended to have poorer mental health, poorer general health and poorer social functioning.

While they also had poorer physical health, the doctors said that this was most likely because the boys were overweight.

However, they also pointed out that the boys had poorer self-esteem and this appeared to be directly related to the breast enlargement rather than the weight problems.

"Merely having gynecomastia was sufficient to cause significant deficits in general health, social functioning, mental health, self-esteem, and eating behaviors and attitudes compared with controls," the doctors from Boston Children's Hospital said.

They noted that while this problem often resolves over time, it will persist in almost one in 10 boys. Furthermore, while most who are overweight or obese will simply be told to lose weight, this will not solve the problem for those with certain types of enlargement - such as enlarged breast glands - or those with a large amount of excess skin.

"As a result, early intervention and treatment for gynaecomastia may be necessary to improve the negative physical and emotional symptoms," the doctors said.

They added that teenage boys presenting with this problem should be regularly evaluated regardless of their weight or the severity of the condition.

Details of these findings are published in the journal, Plastic and Reconstructive Surgery.