GLUCOSE, GROWTH-HORMONE, CORTISOL, AND INSULIN RESPONSES TO GLUCAGON INJECTION IN NORMAL INFANTS, AGED 0.5-12 MONTHS

We performed glucagon stimulation tests in 59 normally growing sibling s of children who died from sudden infant death syndrome. These invest igations were performed to exclude a possible metabolic disorder (foun d in 4 siblings) as an underlying cause of sudden infant death syndrom e. The remaining 55 siblings (32 boys and 23 girls) provide control da ta for this age range. Testing was performed at 0800 h after a 15-h fa st. The median age was 98 days (range, 13-349 days). Plasma glucose an d serum cortisol, insulin, and GH were determined before and 30, 60, 9 0, 120, 150, and 180 min after im injection of 0.1 mg/kg glucagon. No side-effects were observed during the procedure. Asymptomatic hypoglyc emia was noted in 11% of the infants at least once between 120-180 min . Basal and peak GH concentrations were greater than 10 mu g/L in 31% and 80% of the infants, respectively. There was a significant negative correlation between age and basal GH concentration [Spearman's rank c orrelation coefficient (r(s)) = -0.37; P < 0.01]. There was a signific ant correlation between age and glucagon-stimulated cortisol at 120, 1 50, and 180 min (r(s)) = 0.41; P < 0.005), but not between age and cha nges in glucose levels. There was no significant correlation between a ge and basal cortisol or peak GH concentrations and no difference betw een boys and girls for any of the variables studied. In conclusion, th e glucagon stimulation test is well tolerated in very young subjects. The peak GH response to glucagon injection is independent of age betwe en 0.5-12 months. The age-related increase in the glucagon-stimulated cortisol response despite a similar decrease in glucose suggests the e xistence of a postnatal maturation in the response of the pituitary-ad renal axis to stress.