Persistent hyperinsulinemic hypoglycemia of infancy (PHHI) represents the most common cause of hyperinsulinism in neonates; currently, many authors prefer the term congenital hyperinsulinism (CHI). It was first identified in 1938, when Laidlaw coined the term nesidioblastosis to describe the neodifferentiation of islets of Langerhans from pancreatic ductal epithelium (a term since replaced by PHHI and CHI).
Severe recurrent hypoglycemia associated with an inappropriate elevation of serum insulin, C-peptide, and proinsulin levels defines CHI. If left untreated, CHI can lead to brain damage or death secondary to severe hypoglycemia. Although it was initially thought to affect only infants and children, numerous cases have been reported in adults of all ages but at a much lower incidence. CHI is often poorly responsive or unresponsive to medical management, necessitating 95% or near-total pancreatectomy.