Ronaldo, Hypothyroidism and Hair Loss

The Brazilian footballer Ronaldo Luis Nazario de Lima better known as Ronaldo has announced his retirement from the game this month after struggling with injuries and hypothyroidism, a condition that is marked by an underactive thyroid gland which leaves a deficit of thyroid hormone in the blood and can trigger hair loss.

Symptoms of hypothyroidism include difficulty in maintaining body weight, muscle aches and - less commonly reported - hair loss. The thyroid gland produces hormones that are released into the bloodstream to control the body's growth and metabolism, so an underactive thyroid gland can affect hair cells and weaken the hair itself.

"A slowed metabolism can have an effect on hair growth," says Leonora Doclis, senior hair loss specialist at The Belgravia Centre, "Diffuse hair loss is often associated with Hypothyroidism and can affect the scalp or eyebrows. Dry and brittle hair is also commonly seen. These conditions do however revert to normal when thyroid function is restored. Judging by the photo, Ronaldo's hair doesn't seem to have been affected by his condition."

As stated by Doclis, the player is an exception to the general profile of a typical hypothyroidism sufferer. The condition is more likely to appear with age over the year of 40 and women are ten times more likely to have the condition than men. Only one in every 1,000 males suffers from hypothyroidism.

Ronaldo - the leading World Cup goalscorer of all time was emotional when he told the world's press of his decision to retire. He said: ''It's very hard to leave something that made me so happy. Mentally I wanted to continue, but I have to acknowledge that I lost to my body."