South American doctors are trying to find out the reason behind the hefty weight of an 11-month-old baby.

The baby weighs nearly 62 pounds, which is the average weight of an 8-year-old in Colombia, where he was born.

The baby's mother, Milena Orosco de Agudelo, said he began to balloon when he was just 2 months old.

"He had some test done and the results show that he has a thyroid malfunction," said Orosco.

But the doctors are still uncertain.

"The baby will have tests done to see if he's obese or we're dealing with hypothyroidism," said doctor David Dias of the Barranquilla Pediatric Hospital in Colombia.

Hypothyroidism is most commonly a result of an autoimmune condition known as Hashimoto's thyroiditis, in which the body's own immune cells attack and destroy the thyroid gland. Symptoms include fatigue and weight gain.

The normal weight for a boy his age is between 13 and 16 pounds.

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