Diagnosis of congenital hyperinsulinism: Biochemical profiles during hypoglycemia.

OBJECTIVES: To define the ranges of biochemical markers during hypoglycemia for the diagnosis of congenital hyperinsulinism (CHI), using high sensitivity insulin assays.

SUBJECTS: A total of 298 patients with CHI and 58 control patients with non-hyperinsulinemic hypoglycemia, who were diagnosed after 2007.

METHODS: The levels of biochemical markers (glucose, insulin, β-hydroxybutyrate [BHB], free fatty acids [FFA], lactate, ammonia) at the time of hypoglycemia were analyzed along with the maximal glucose infusion rate (GIR) to maintain euglycemia and clinical outcomes.

RESULTS: Median levels of blood glucose in patients with CHI and in controls were 30 and 46 mg/dL, while insulin levels were 9.90 and undetectable (<.5) μU/mL, respectively. Similarly, median levels of BHB were 17.5 and 3745 µmol/L, and those of FFA were 270.5 and 2660 µmol/L, respectively. For patients after 5 months, cutoffs of insulin >1.25 μU/mL, BHB < 2000 µmol/L, and FFA < 1248 µmol/L predicted CHI with sensitivities of 97.5, 96.2, and 95.2% and specificities of 84.2, 89.3, and 92.3%, respectively. Maximal GIR in the CHI groups tended to decrease with age. In addition, decreased gestational age, low birth weight, and elevated lactate at hypoglycemia were significantly more common in patients who were off treatment within 100 days without pancreatectomy.

CONCLUSIONS: After introduction of high-sensitive assays, the diagnostic value of insulin was improved, allowing for more efficient cutoffs to be set for diagnosis of CHI. Premature birth, low birth weight and elevated lactate might be helpful in predicting early remission of hypoglycemia.