Endogenous hyperinsulinism is the leading cause of persistent
hypoglycemia in children under one year of age. Classically, the symptoms of neonatal
hypoglycemia have been referable to central nervous system dysfunction, with
seizures described in nearly all patients. Our experience with eight neonates emphasizes the protean manifestations of this disease. One patient presented with a maternal history of
diuretic use, and developed asymptomatic
hyperinsulinism documented by provocative testing. The
hyperinsulinism cleared after two weeks of medical
therapy. This transient
hyperinsulinism may have been secondary to use of a
thiazide-type
diuretic. A second patient presented, as a neonate, with a large abdominal mass but no seizure activity. Exploratory
laparotomy revealed an 11 x 5 x 3 cm pancreatic
tumor, which required
splenectomy, 60%
gastrectomy and duodenectomy for removal. Histologic examination demonstrated an
insulin-secreting
hamartoma. A third patient died suddenly without prior symptoms, and was found to have striking
nesidioblastosis on pathologic examination. One infant presented with absence of the abdominal musculature (
prune belly syndrome) and features of the Beck-with-Wiedeman syndrome, as well as profound
hypoglycemia. Only three patients had
seizures, and an additional patient had jitteriness. Pathologic diagnoses were:
nesidioblastosis (n = 2); islet cell
hyperplasia (n = 1);
adenoma (n = 1);
hamartoma (n = 1); transient
hyperinsulinism (n = 1). One patient's pancreas showed areas of
nesidioblastosis, islet cell
hyperplasia, and a discrete
adenoma in the region of the common bile duct. Careful diagnostic testing is essential in these patients, inasmuch as
hypoglycemia is poorly tolerated by neonates and infants. Using the diagnostic algorithm presented here, all patients'
endogenous hyperinsulinism was documented quickly and efficiently. Recognition of the broad spectrum of symptoms with which these patients may present is essential if serious neurologic sequelae are to be avoided.