PSUN340 Two cases of diffuse form of diazoxide-responsive congenital hyperinsulinism confirmed by 18F-DOPA PET-CT

INTRODUCTION: Congenital hyperinsulinism is one of the most common causes of severe hypoglycemia in infants. Brain can be more damaged in the situation of hypoketotic hypoglycemia because there are no sufficient ketones for brain metabolism. Some patients develop severe symptoms during the newborn period, others at a later age. Several genes including ABCC8, KCNJ11, GCK, GLUD1, and HNF1A are reported as the candidate genes of congenital hyperinsulinism and 18F-DOPA PET-CT can be used to detect the location. CLINICAL CASES: Case 1. A 9-year-old girl, born at 38 weeks, 3.12 kg, without any perinatal problems, developed hypoglycemic seizure at the age of 65 days for the first time. The levels of blood glucose, insulin, C-peptide, cortisol, and ammonia were 42 mg/dL, 37.14<img src="data: image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAoAAAARCAIAAABrQaqyAAAAAXNSR0IArs4c6QAAAAlwSFlzAAAOxAAADsQBlSsOGwAAAF5JREFUKFNj/P//PwNuwIRHDig1RKTvTLRmTN8O9sr2dEbriXfo7PIrt4A23tm+4Qo0NIFhDgO3J1gBAQODVdq229vSgPJWaQxo0hNuIwn8/48W5seu3UaJI0aKIhQA19xAJDTBqMgAAAAASUVORK5CYII=">U/mL, 4.20 ng/mL, 21.85 ug/dL and 54 ug/dL, respectively. Diazoxide was started and she was referred to our institute at 9 months old. The levels of glucose, insulin, and C-peptide, and cortisol performed at the age of 13 months with medication of diazoxide (7.7 mg/kg/day) were 4 7mg/dL, 5.5 <img src="data: image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAcAAAARCAIAAACevyECAAAAAXNSR0IArs4c6QAAAAlwSFlzAAAOxAAADsQBlSsOGwAAAFtJREFUKFNj/P//PwMGYMIUAorQXfTORGvG9O1gt2xPZ7SeeIeKbrhyC2jane0brkC9+v//7QlWQMDAYJW27fa2NKCwVRoDRHTCbWAoIQAkHI5du40SSowkhCQAYbsuNpK0C5QAAAAASUVORK5CYII=">IU/mL, and 0.7 ng/mL, and 32.4 ug/dL, respectively. She admitted several times due to hypoglycemia which associated with poor oral intake during acute febrile illness. Diazoxide dosage had been increased according to the situation until 7 years old. Genetic investigation including whole exome sequencing did not show any pathogenic mutation. She grew well and showed normal development. Now she is on diazoxide medication but the dosage can be reduced to 3.7 mg/kg/day. 18F-DOPA PET-CT was performed to see the pathologic extent which revealed diffusely increased uptake from head to tail of pancreas. Case 2. A 25-month-old boy, born at 37+3 weeks, 2.9 kg, without any perinatal problems, was diagnosed with epilepsy at the age of 6 months. Hypoglycemic seizure was first identified at the age of 11 months when he was admitted to our institute due to severe hypoglycemia combined with seizure. The levels of blood glucose, insulin, C-peptide, cortisol and ammonia were 35 mg/dL, <img src="data: image/png;base64,iVBORw0KGgoAAAANSUhEUgAAACMAAAARCAIAAADYCYKoAAAAAXNSR0IArs4c6QAAAAlwSFlzAAAOxAAADsQBlSsOGwAAAMBJREFUSEvdVcENwyAMhI5l9sHrhE36gg0yAcojsAt1EmhIZQVFVfLAL3w6Y+t8CJlSEo/E65EuS5OeO0VnUKE7asmCNaVJqMikXnSIGObJjxXOgscmTNXp0sl7a4QBhLYlOwNrDlv1c0lOb3JENErmXTiUysS+vXf/A764JxK96N+czc+0nejePjNX22kodQB6CJsXGTBZLYpDecJuWgC6FLQNSw0dBG/Jf1FyP2wTf+Oiek3JdsI4hQNbdvhrfACYFi2Z8Bo2twAAAABJRU5ErkJggg==">U/mL, 2.9 ng/mL, 18.5 ug/dL and 40.4 ug/dL, respectively. Diazoxide was added to the antiseizure medication. He admitted several times due to seizure which was not associated with hypoglycemia. He also showed global developmental delay. Now he is still on diazoxide medication with dosage of 6.4 mg/kg/day. 18F-DOPA PET-CT revealed diffusely increased uptake from head to tail of pancreas. CONCLUSION: Here we report two cases of diffuse form of diazoxide-responsive congenital hyperinsulinism confirmed by 18F-DOPA PET-CT. Presentation: Sunday, June 12, 2022 12:30 p.m. - 2:30 p.m.