[Diagnostic evaluation of persistent neonatal hypoglycemia using the fasting test: behavior of glucoregulatory hormones and intermediary metabolites (1)]

Abstract

The effect of insulin induced hypoglycemia on glucoregulatory hormones and intermediary substrates was studied in four infants (three boys and one girl, ages 12-89 days) with persistent hyperinsulinism secondary to nesidioblastosis (two) or microadenoma of the pancreas (two). During the "fasting test" the following data expressed as mean basal plasma values +/- SEM vs. mean hypoglycemic values +/- SEM were obtained: insulin (57.3 +/- 17.9 vs. 27.5 +/- 10.6 microU/ml), C-peptide (4.9 +/- 1.1 vs. 3.5 +/- 0.9 ng/ml), free fatty acids (0.30 +/- 0.01 vs. 0.32 +/- 0.02 mmol/l), beta-hydroxybutyrate (less than 0.03 vs. 0.05 +/- 0.02 mmol/l), alanine (204.0 +/- 67.5 vs. 228.3 +/- 64.9 mumol/l), lactate (5.3 +/- 0.7 vs. 5.4 +/- 1.1 mg/dl), pyruvate (41.3 +/- 4.8 vs. 19.7 +/- 4.2 mg/dl). These data suggest "inappropriate" elevation of insulin and C-peptide levels, inhibition of lipolysis and lack of gluconeogenic substrates secondary to endogenous HI. An increase of cortisol (6.5 +/- 4.1 vs. 16.3 +/- 5.7 micrograms/dl), adrenaline (0.015 +/- 0.05 vs. 0.25 +/- 0.24 ng/ml) (3 out of 4) and noradrenaline (0.28 +/- 0.06 vs. 0.64 +/- 0.14 ng/ml) was noted, whereas only minute increase was found for glucagon (134.3 +/- 51.7 vs. 177.0 +/- 76.2 pg/ml) and HGH (5.7 +/- 1.1 vs. 7.1 +/- 1.1 ng/ml). Although some stimulation of neonatal glucoregulatory hormones was evident, this was not strong enough for counteracting endogenous HI.