Like a lot of boys growing up, Dr. Thornton’s interest centered on athletics. He calls himself a “sports fanatic,” playing rugby, cricket, tennis and swimming. As a kid, he played more than studied.

So when Dr. Thornton told his guidance counselor in high school that he wanted to become a doctor, the counselor told the man who would become a world expert in a rare disease that he needed a back-up plan.

What the guidance counselor didn’t understand just yet was that Dr. Thornton’s focus from an early age was on science and medicine. Dr. Thornton saw something in himself that nobody else saw.

“When I said I wanted to be a doctor they told me I should have a backup plan,” Dr. Thornton says now with a twinkle in his eye. “So that was always fascinating to me. I wasn’t the guy people thought was the most intelligent person in the class. Now I’m a world expert in a disease. Once I became a doctor, I realized where my true passion was and I followed it.”

Congenital Hyperinsulinism

Dr. Thornton resides at Cook Children’s as the medical director of the Endocrine and Diabetes Program and the Hyperinsulinism Center. He played a vital role in establishing the first two centers for congenital hyperinsulinism (CHI) in the nation.

His congenital hyperinsulinism program at Cook Children’s celebrates its tenth anniversary this year. The genetic forms of HI affect only between 80 and 120 babies each year. For those affected by the rare condition, it can be a life-changing event. Without an accurate diagnosis, children face living with seizures and permanent brain damage.

The program gives many patients an opportunity for a cure because of the expert staff and the use of an investigational new drug called 18F DOPA in combination with a PET-CT scan to more accurately diagnose and treat HI.

The 18F DOPA/PET-CT scan serves as a diagnostic test that has altered the treatment and even led to cures for children with certain forms of hyperinsulinism. Cook Children’s remains the only facility in the south and the second in the country to use 18F DOPA – an investigational drug – in combination with a PET-CT scan to diagnose focal lesions in children with congenital hyperinsulinism.

Dr. Thornton leads a team of physicians specialized in endocrinology, pediatric surgery, neonatology, neurology, gastroenterology, pathology and radiology. The team is supported by a dedicated HI nurse practitioner, social worker, clinical therapist, child life specialist, nutritionist and feeding and speech therapists.

At the heart of the program is Dr. Thornton, one of the most recognized and respected HI specialists here and around the world.

The Expert

To show what a leader he is in the field, Dr. Thornton’s served as lead author for an article titled “Recommendations from the Pediatric Endocrine Society for Evaluation and Management of Persistent Hypoglycemia in Neonates, Infants and Children.” This article established the groundwork in creating new screening for physicians to recognize and manage neonates at increased risk for a persistent hypoglycemia disorder.

The guidelines help physicians recognize the symptoms of uncontrolled hypoglycemia caused by CHI who are at risk for seizures or permanent brain damage without early identification and screening.

Dr. Thornton’s recognition as a leader earned him one of the first two endowed chairs at Cook Children’s. He’s a recipient of the Rare Disease Hero award, which recognizes only five physicians each year for groundbreaking research and treatment in the rare disease community.

He’s come a long way from what Dr. Thornton calls his “quirky story.”

Growing Up

Dr. Thornton grew up in a middle-class family in Ireland. His grandfather ran the water department for the government, responsible for water purity for the country. His father did not go to college but rather became a businessman.

Little did Dr. Thornton know how hard his father worked to give his children an opportunity to continue their education.

“I went to a private Catholic school. This is going to sound really strange, but I did not know it was a private school,” Dr. Thornton says while laughing at the thought. “You know in Ireland, everyone wears a school uniform. It’s not like in the States where only private school kids wear one. And it’s not like here, where there’s a private school at every stone’s throw. It just never dawned on me. Later my father said, ‘Do you know how hard we had to work to pay for that school?’”

Maybe it’s that example of hard work that led to Dr. Thornton earning his medical degree by the age of 23, the culmination of a childhood dream.

“It’s funny because there was almost nothing else I ever wanted to be. I knew from the age of 12 that I wanted to be a doctor,” Dr. Thornton said. “I think it was probably because of our family practitioner (Dr. Brendon Deasy). Dr. Deasy was a really good friend of the family, so I got to know him very well. I went to see him professionally every year. I realized that the work of a doctor was a really nice career. You got to meet new people every day. You got to help people. He is probably responsible for showing me what a great job being a physician could be.”

Dr. Thornton went to college without a backup plan. He knew once he got into university and could focus on studying to be a doctor, he would excel.

A Pediatrician

Once his clinical rotations began, Dr. Thornton decided early on that pediatrics was for him.

“When you work with children, they are restorative. You can’t come in grumpy.. You end up having fun doing your day’s work,” Dr. Thornton said. “It never seemed like a lot of fun dealing with adults all the time.”

What did seem like fun was endocrinology. Although his focus came about through a bit of circumstance and travel.

In medical school, Dr. Thornton excelled and “fell in love with learning.” He begins to get noticed too and that eventually led him to Great Ormond Street Hospital (GOSH) for Children, the oldest and one of the most prestigious pediatric hospitals in the world. This job was part of a job exchange with residents from the Children’s Hospital of Philadelphia, so Dr. Thornton headed to the States for a year

Dr. Thornton pauses for a moment thinking about his arrival in the United States.

“I only spent 28 years of growing up in Ireland. I left for England at 28 and came to the U.S. at 29. So actually, I spent less than half my life in Ireland. Wow!”

At CHOP, Dr. Thornton met the mentors who changed his life. He learned about endocrinology and specifically, hypoglycemia. “It didn’t take me long to determine that’s what I want to do with the rest of my life,” he said.

“I was very lucky that I trained at the only place, at the time, that had that sort of hypoglycemia program,” Dr. Thornton added. “So two of the doctors (Lester Baker and Charles Stanley) out of my four attending physicians were the world experts in hypoglycemia. It was just fascinating. The patients we were seeing were very difficult kids to manage.”

At the end of his year commitment, Dr. Thornton planned on returning to England, but CHOP offered him a fellowship to stay. He wrote GOSH a letter that said he wasn’t going back to London.

Returning to Great Ormond Street meant Dr. Thornton couldn’t stay on his new chosen career path. He wanted to learn more about treating children with hypoglycemia. Dr. Thornton did return to Ireland from 1996-1999 but eventually went back to CHOP where he remained until 2002 when he got a call from a recruiter.

Welcome to Cook Children’s

Dr. Thornton admits now he’d never heard of Cook Children’s or even Fort Worth when approached about a new job. He turned the recruiter down. Then a few months later, Dr. Thornton presented a paper at a Pediatric Society meeting. The recruiter showed up to hear him speak and invited Dr. Thornton to breakfast for one final pitch.

The recruiter showed Dr. Thornton pictures of the medical center and information about the institution. They ended up talking for four hours.

Following a trip to Fort Worth and a visit to Cook Children’s, Dr. Thornton accepted the role of medical director of Endocrinology.

“Now I still had so much to do. When I got here there were only two doctors. The waiting time was something like nine months,” Dr. Thornton said. “We had to do a lot of work to get the place how I wanted it. Everyone was good people and everyone was working hard. They just needed new leadership and some organization. So the first two or three years was building the program, hiring nurse practitioners and doctors. I focused on the organizational things and developing protocols.”

Soon, the department blossomed and Dr. Thornton became very busy not only as an administrator but seeing patients. However, something remained that lurked in the back of his mind since his arrival at Cook Children’s.

“I reached a position where I had time to think about my future here in Cook Children’s, ‘I had a skillset and focus on hypoglycemia and congenital hyperinsulinism (CHI). I decided to approach the hospital and say, ‘I'd like to set up a new hyperinsulinism center and develop a surgical program for the babies with HI.’ We wrote a proposal and it was like ‘Boom!’ They said, ‘yes.’”

Building a Program

After helping to launch the first such program in the nation, Dr. Thornton knew what he wanted when he began the second one at Cook Children’s. He brought a nurse coordinator/ nurse practitioner, Lisa Truong, CPNP-AC, to help him with the day-to-day operations.

“When Dr. Thornton asked me to join, I was very excited. It was a challenge to build a program from scratch. Ten years later, it’s still a challenge but I love it. All the kids we see are completely different because it’s such a rare condition. No kids present the same, which I like because it keeps me on my toes. I have learned so much from Dr. Thornton throughout these 10 years. He is an awesome boss and a great mentor."

Over the next three to five years, the program continued to grow and build. Cook Children’s showed their support for the program by naming Dr. Thornton one of the first two endowed chairs in the history of the program. Everything clicked.

Even after all this time, nothing thrills Dr. Thornton more to give good news to the families he treats. He continues to carry on a tradition of taking pictures with his families and marvels at their excitement when things go well.

“They realize that ramifications of what life means for them now that their child’s cured,” Dr. Thornton said. “A lot of these families don’t understand what it will mean to their life until it happens. And then it’s a big shock when they get home and realize, ‘Oh my God, I don’t have to check on my baby’s blood sugar eight or 10 times a day. The difference is so huge. You can just see how very happy the family is when there’s a cure.”

If only that guidance counselor could see him now.

Almost half of the people who participated lost an average of 30 pounds, went into remission and were no longer diagnosed with diabetes. They did not take any medications during this time and relied solely on weight loss. “Remission of type 2 diabetes is a practical target for primary care,” the authors of the paper wrote.

The participants in the study were on a liquid diet of 825 to 853 calories daily for three to five months and then were reintroduced to solid food, while maintaining a structured diet over the course of a year.

All the individuals who participated in the study were adults (20-65 years of age).

Joel Steelman, M.D., an endocrinologist at Cook Children’s, said that weight loss has been especially effective in treating adults, whether through diet or after weight loss surgery, and can lead to de-escalation of treatment or stopping therapy. This has been especially true in adults, whether through diet or after weight loss surgery.

Dr. Steelman said children with type 2 diabetes will also benefit greatly from weight loss, but an extreme low calorie diet, like the one the participants in the adult study were on, is a bit more of a concern in a still growing, developing child. Dr. Steelman said pediatric endocrinologists focus on eating a healthier, lower calorie, lower carbohydrate diet, while also stressing the child becomes active.

“Weight loss and improved diet often leads to de-escalation of treatment for children – stopping insulin often and sometimes stopping oral medication,” Dr. Steelman said.

But a child can’t make extreme lifestyle changes without the entire family buying in and everyone in the household living healthier. A child needs the full support and active involvement from all family members. Therapeutic lifestyle changes need to last a lifetime.

“It’s essential for the parents to be extremely involved. You to have buy-in and support from the family,” Dr. Steelman said. “There’s often type 2 diabetes in one of both parents. It’s a no-brainer that the whole family will experience some benefit, whether immediate or future, from improving food choices and increasing activity. It’s critical to understand that type 2 diabetes is a deadly disease, and is associated with earlier and more frequent cardiovascular disease and premature mortality than type 1 diabetes mellitus.”