IGF1 and hypopituitarism: On the other hand, adolescents with low-normal serum IGF1 (near the age-related lower limit or between -2 and 0 SD) and a peak GH < 6 μg/L but no additional or only one associated pituitary hormone deficiency require a second GH stimulation test with another secretagogue (preferentially glucagon) given the known variability of peak GH values at ITT/GST testing and basal serum IGF1 levels.