Hypoglycemia in infants and children.

Although the conditions that cause hypoglycemia in adults may also be present in infants and children, there are many entities unique to the pediatric age group. This reflects the delicate balance that exists in the newborn and young child between glucose production and utilization. During fasting in infants and children, hepatic glucose production is normally two to three times that of adults when expressed on the basis of weight. In the newborn and young infants, hypoglycemia usually presents with irritability, feeding difficulties, lethargy, cyanosis, tachypnea, and/or hypothermia rather than the typical adrenergic or neuroglucopenic symptoms seen in the adult. The hypoglycemia may be due to abnormalities in hormone secretion, substrate interconversion, or mobilization of metabolic fuels. The hypoglycemia associated with hyperinsulinemia may be transient neonatal, sustained, or drug-induced. Inborn errors of metabolism caused by enzymatic defects are responsible for hypoglycemia associated with abnormalities of production and utilization of metabolic fuels. These can involve carbohydrate, protein, and fat metabolism. In addition, there may be acquired or transient defects in carbohydrate metabolism secondary to other diseases or ingestion of certain substances. Finally ketotic hypoglycemia appears to be due to abnormalities in substrate availability. A variety of tests are useful for establishing the etiologic basis of the hypoglycemia, and the appropriate treatment depends upon the underlying cause.