Neonatal hypoglycemia in a growth hormone registry: incidence and pathogenesis

OBJECTIVE: To examine the characteristics of infants with neonatal hypoglycemia treated with growth hormone (GH) in order to gain insights into factors aiding in the identification of and timely treatment of hypopituitary neonates. STUDY DESIGN: The National Cooperative Growth Study (NCGS) database was examined to identify infants with neonatal hypoglycemia started on GH by 6 months of age. 169 infants (100 males, 69 females) were found and their data analyzed for physical characteristics, the presence of other hormone deficits, and the diagnostic methods used. RESULTS: Mean +/- SD baseline length standard deviation score (SDS) was -1.5 +/- 1.8. 148/169 infants had hypopituitarism. Twelve had isolated GH deficiency (GHD). Nine had hypoglycemia without hypothalamic or pituitary pathology. Structural central nervous system (CNS) lesions and/or midline facial defects were present in 66/169. 55/100 males had micropenis. Although 158 infants had GHD, only 90 infants had it documented by stimulation testing (80) or a critical sample when hypoglycemic (10). Multiple hormone replacement therapy was necessary in 89% of the hypoglycemic infants. CONCLUSIONS: The great majority of these hypoglycemic infants had GHD, usually secondary to hypopituitarism. Over 1/3 had structural lesions of the hypothalamic-pituitary area or midline facial defects. Although lengths may be normal in these infants, physical features such as micropenis or cleft lip and/or palate should suggest pituitary dysfunction as the etiology of their hypoglycemia. A critical blood sample for GH taken during hypoglycemia is a quick and definitive diagnostic tool.