A BRAVE Greenock girl has such a rare metabolic disorder that she could slip into a coma by eating a chicken nugget.

Little Kaitlyn Branchfield was diagnosed with ornithine transcarbamylase (OTC) deficiency when she was just 15 months old — a condition that affects just one in every 80,000 people.

The genetic illness means the five-year-old’s body is unable to get rid of harmful ammonia, which if allowed to build up will start to attack her brain and vital organs – and could cause irreparable damage.

Kaitlyn’s mum, Eileen Rooney, told the Telegraph: “Kaitlyn will never be able to have a steak, chicken or anything like that. Any meats or anything that’s high in protein in general. She can’t have a roast dinner.

“You have to look at everything you buy as it has your protein allowance on it.

“If we go to the likes of McDonald’s or if we feel like going out for a meal I have to take my scales and bowl and weigh things.

“She can’t eat a chicken nugget. The only thing she can get is a small portion of French fries which is about three grams of protein.”

OTC deficiency is largely produced during the breakdown of food, particularly protein, and as a result Kaitlyn is on a strict diet and can consume no more than five grams of it a day.

It means that as little as a chicken nugget, or even a small yoghurt, could push her over the limit and lead to lethargy, vomiting and even push her into a coma.

Eileen, 30, said: “She’s right into baked potato and tuna right now, but again I have to use my scales.

“We can’t order from a menu for her. I phone before we go anywhere and explain that my daughter has a disorder.

“If she gets too much protein or she doesn’t get enough medicine she gets lethargic and the ammonia will attack her body.

“She would have to go into hospital and would get a very high dose of intravenous medicine into her veins to flush the ammonia out as much as possible. Then it’s a case of hoping it hasn’t done too much damage.

“You really don’t want it to get too that stage.”

Kaitlyn receives specialist medicine four times a day just to allow her to consume protein — which is vital for the body to build and repair — as well as a food supplement to ensure she gets all the vitamins and minerals she needs.

Both are administered via a tube through her nose, but the youngster will soon have a procedure which will see a ‘peg’, or button, put in her stomach to make the medicating process easier.

Her daily protein limit is 15 grams but the majority of that comes from her supplements meaning she is severely restricted in what she can eat.

Kaitlyn has to have blood samples taken every three months and her diet and medication is adjusted accordingly.

Mum Eileen, who is originally from Port Glasgow, said: “The best way to describe it is it’s similar to diabetes in that it’s metabolic and where diabetics can’t take too much sugar but Kaitlyn can’t have too much protein because it produces ammonia.”

The youngster, who lives in Greenock town centre with her mum, dad Alan Branchfield and one-year-old twin brothers John and Connor, also has a form of autism after suffering brain damage when she was little more than a year old, prior to being diagnosed with OTC.

At one point her parents were told that she might not survive after being put in a medically-induced coma, and even if she did come through it the tot might be in a ‘vegetative state’.

But Kaitlyn made a miraculous recovery and despite everything she has been through at such a young age, the energetic little girl doesn’t let her condition hold her back and will soon start at Craigmarloch School in the Port.

In tribute to the work of medics, and particularly those at the former Yorkhill Children’s Hospital which is now based at the Queen Elizabeth University Hospital in Glasgow, her relative Rob Bliss, pictured above with Kaitlyn and Eileen, has signed up to the Greenock Morton Community Trust 50 day 5k challenge.

Proceeds from the 5k challenge will also go towards the Ton’s charitable arm, which has helped Rob lose over three stones through its Football Fans In Training Programme, and medics at the metabolic unit.

Rob, who lives in Greenock, said: “I like challenges and it’s another thing to keep me on track with walking more and being in the right mindset of losing weight.

“I thought about which charity I was going to support and my wife Lisa mentioned about Kaitlin and the metabolic unit in Glasgow.

“They are always striving for funding and the money goes straight to the unit.”

To donate visit www.justgiving.com/robin50kbliss