Persistent neonatal hypoglycemia: Diagnosis and management

Maintenance of plasma glucose depends on a normal endocrine system, functional enzyme levels for glycogenolysis, gluconeogenesis and other processes, and there must be an adequate supply of endogenous fat, glycogen and substrates of gluconeogenesis. Neonatal hypoglycemia should be defined as serum glucose less than 2.2 mmol/L in the first 72 h of life and less than 2.5 mmol/L thereafter. The purpose of this paper is to review the more uncommon causes of hypoglycemia in the full term, apparently healthy neonate. Most of these conditions are inborn errors of metabolism. A protocol for investigation of these conditions and some of the more common diseases, such as hyperinsulinism, is provided, with a rationale explaining why these tests may be helpful.