HNF1A-hyperinsulinism: Bryce's Story

Six-month-old Bryce Parry goes to sleep around 8 at night and sleeps a good 11 or 12 hours until waking up. Sounds like a parent’s dream baby, right?

Baby Boy Bryce with Family Karen and Ryan Parry with Bryce and Liam Not necessarily. Bryce was diagnosed with hyperinsulinism (HI) at 3 weeks old, and when his mother, Karen Parry, checks his blood sugar in the morning, it’s sometimes low, around 55 mg/dL. “Since home glucose meters can be off by 20 points, it could mean he’s really at 35 — and that scares me,” Parry says.

A quick call to the Congenital Hyperinsulinism Center at The Children’s Hospital of Philadelphia, where Bryce has been treated since he was 2 weeks old, and Parry had an answer: Increase his dose of diazoxide to cover his long night’s sleep.

Bryce’s treatment is a bit more complicated because he has a rare form of HI called HNF4A HI, named for the defective gene responsible. Children with HNF HI have comparatively mild hypoglycemia, can be treated with diazoxide alone (no continuous dextrose feeds or surgery required) and will typically outgrow it. The genetic defect also means they will get diabetes later in life. Even a place like CHOP’s HI Center, which treats more HI patients than any center in the United States, sees only a handful of children with HNF each year.

Bryce was born large for gestational age, 8 pounds, 7 ounces at 36½ weeks. Since Parry had gestational diabetes, his size wasn’t unexpected, nor was that he had hypoglycemia at birth. The family’s first son, Liam, now 3, had low blood sugar for the first 24 to 48 hours of his life, but it rose to a normal level and stayed there.

Baby Boy Bryce with brother LiamBut Bryce’s blood sugar stayed low, despite intravenous glucose. After two weeks, Bryce was transferred to CHOP.

“We learned he had HI after a day or two at CHOP,” Parry says. “He was controlled with diazoxide, and we came home after a week. He ate five times a day, and I checked his sugars three times a day. He was doing really great on it. He was on a good path.”

It wasn’t until a couple months later that the genetic test results showed that Bryce had HNF4A HI. It also meant that one of his parents, Parry or her husband Ryan, had diabetes or was at risk for it. Parry ended up carrying the gene trait. “My endocrinologist says I don’t have it right now, but we’ll check it every few month,” she says. If she has to check her own blood sugars as part of treatment, that’ll be a snap. She already checks Bryce’s “constantly.” It was her diligent care that showed the trend of his morning lows as he was growing and eating more.

All that growing meant Bryce needed more diazoxide to keep his blood sugar in the safe range and avoid any dangerous lows.

“He’s very active, meeting all his milestones,” Parry says. “He’s rolling over, tracking objects and grabbing them.

And he’s a great sleeper.” Now that Bryce’s HI is controlled, Parry can get a good night’s rest, too.


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