Doctors told him he must have risky brain surgery to stop him growing further – or his organs will fail and he will die.
Gabriel Gomes suffers from gigantism, a serious disorder caused by a tumour of the pituitary gland. This means his body produces too much of a growth hormone.
It is related to the condition actor Richard Kiel, who played Jaws in The Spy Who Loved Me, suffered from.
A documentary called Body Bizarre follows the boy, from Brasilia in Brazil, as he undergoes the delicate operation to remove the tumour in a bid to lower his hormone levels.
Gabriel explains how his height takes both a physical and emotional toll on him.
'It bothers me that I'm quite tall, I want to be normal,' he said. 'I feel pain, my legs ache a lot. Sometimes I suffer from back pain because I have a hunched back.
The youngster just wants to be like every other 12-year-old.
'I am not studying because it is difficult to find a vacancy as I am very tall, it's really difficult. I hope that I will be able to study after the surgery,' he added.
Gabriel had surgery when he was 10 and spent a month in hospital.
However, while the operation was safe – doctors reached his brain by going in through his nose – they were unable to remove all the tumour and it has continued to grow.
'I thought he'd die,' said his mother Ricardene.
Now, two years on, Gabriel's need for surgery is urgent. If the operation fails, there is nothing that will stop his body from growing and his organs will fail.
Hormone expert Dr Flavio Cadegiani said: 'Gigantism is a very rare disease that compromises the life of the patient. This patient is very likely to die in the following 15 years. So he has to go under a new surgery.'
Ricardene tells the viewers that Gabriel has bravely endured far more than most children his age.
'I hope he comes out a different person,' she said. 'To experience a normal life, as he's never had one.
'I hope it's all worth it after so much suffering, nobody deserves to go through this. It's really tough.'
In a sweet moment before he is put under, he tells Ricardene, 'You are the love of my life. Pray for me please.'
Outside the operating theatre, Gabriel's mother Ricardene is in a state of high anxiety.
After eight hours at work, the team finally remove the tumour that has caused Gabriel's excessive growth.
But when the surgery is over, the medics struggle to wake him. He has not fully regained consciousness and seems to be paralysed on the right side of his body.
Doctor Sanders said: 'There might be a lesion in the system responsible for the movement of the right side of his body, but it's too early to tell.'
The youngster is taken for an emergency brain scan. They discover he had suffered a a blood clot leaving him paralysed down one side of his body.
As he is rushed to intensive care, lead surgeon Doctor Cescato explains to Ricardene that although the tumour has been removed, there were complications.
'We don't know for how long or how much he will recover,' he said.
An emotional Ricardene said: 'My God. I can't accept it. I've put an end to my son's life.'
Miraculous recovery
Gabriel's mother is warned that the next few hours will be critical.
Thankfully, treatment of blood–thinning medication has led to an astonishing turnaround and the boy wakes up and seems to have made a miraculous recovery.
Now fully conscious, he can move both sides of his body. He must now have intensive physiotherapy to help him recover.
Ricardene said: 'I thought I was going to lose him, but thank God he is much better.'
Fortunately for Gabriel, his blood flow has returned to normal, there is no further risk of a blood clot to his brain or any complications with his heart.