PMON313 Hyperinsulinemic Hypoglycemia and Growth Hormone Deficiency Secondary to 20p11 Deletion

INTRODUCTION: Hyperinsulinism (HI) and growth hormone deficiency (GHD) are known causes of hypoglycemia but not commonly found together. We present a 4-month-old boy with hypoglycemia found to have both HI and GHD with subsequent genetic diagnosis of 20p11 deletion. This deletion has been associated with panhypopituitarism. This case represents a few to report HI as a manifestation of this deletion. Treatment with both recombinant human growth hormone (rhGH) and Diazoxide led to blood glucose (BG) normalization. CLINICAL CASE: A 4-month-old, full-term, large for gestational age (96th percentile), born to a nondiabetic mother presented with hypoglycemic seizures. He had transient hypoglycemia at birth, normal newborn screen, and exclusively breastfeeding with normal growth and development. He had a negative 60-hour video EEG. Further work-up was significant for serum glucose of 54 mg/dL despite blood draw being 20 minutes after a breastfeed, prompting endocrinology evaluation. Physical exam showed no dysmorphism and normal genitalia. He had a serum glucose of 39 mg/dL while asymptomatic. Critical sample revealed detectable insulin (3.2 mcIU/mL), low beta hydroxybutyrate (145.6 mcmol/L) and low growth hormone (GH) (4.2 ng/dL). He had normal cortisol, lactic acid and ammonia. A glucagon challenge showed an increase in BG of 26 mg/dL (35-->61 mg/dL). He had a GH stimulation test with arginine (peak GH 3.8 ng/dL) and glucagon (peak GH 6.6 ng/dL). He had mildly elevated liver enzymes that resolved on repeat testing. Plasma amino acid, plasma acylcarnitine profile, urine organic acids, and brain MRI were normal. He was initially started on rhGH with continued hypoglycemia, hence, Diazoxide, and chlorothiazide were added. His BG was monitored until dextrose infusion was successfully weaned, while maintaining normoglycemia. Genetic testing with next-generation sequencing revealed 20p11.22-p11.21 deletion. He was discharged on Diazoxide (12 mg/kg/day), chlorothiazide, and rhGH (0.27 mg/kg/week). CONCLUSION: It is important to determine the cause of hypoglycemia so specific treatment can be provided. HI is a common cause of hypoglycemia in infants due to abnormal insulin secretion in the pancreatic beta cells. GHD can also cause hypoglycemia and be associated with other pituitary hormone deficiencies. Evaluation of our patient's hypoglycemia revealed HI, GHD and 20p11 deletion. This deletion has been associated with hypoglycemia due to GHD and few reports with HI. This patient will need to be regularly screened for other pituitary hormone abnormalities. Other features of 20p11 deletion include cognitive delay, craniofacial dysmorphisms, gastrointestinal and genitourinary anomalies. While hypoglycemia is often the result of a single cause, this case shows that there are pathological conditions that can present with both GHD and HI, so the differential diagnosis for hypoglycemia should remain broad. Presentation: Monday, June 13, 2022 12:30 p.m. - 2:30 p.m.