The growth hormone response to pyridostigmine plus growth hormone releasing hormone is not influenced by pubertal maturation

Abstract

We have evaluated the effect of pubertal maturation on the GH response to growth hormone releasing hormone (GHRH), pyridostigmine (PD) and the combined administration of PD + GHRH in a group of short normal children. Fifteen were prepubertal (13 boys and 2 girls, age 5.0 - 12.5 yr), 10 were early pubertal (8 boys and 2 girls, age 11.5 - 16.9 yr in Tanner stage 2-3 of pubertal maturation), and 6 were late pubertal (6 boys and 2 girls, age 13.6 - 17.1 yr in Tanner stage 4-5 of pubertal maturation). All subjects were tested on three occasions with GHRH 1-29 (1 microgram/Kg iv), PD (60 mg po) and PD + GHRH (60 mg PD administered orally 60 min before GHRH). Peak GH levels after GHRH, PD, and PD + GHRH in the prepubertal children (16.0 +/- 2.8, 8.1 +/- 1.3 and 51.1 +/- 5.5 ng/ml, mean +/- SE, respectively) were not different from those observed in the early pubertal (18.4 +/- 2.1, 9.1 +/- 1.9 and 41.2 +/- 5.6 ng/ml, respectively) and in the late pubertal group (14.9 +/- 2.3, 13.1 +/- 2.4 and 42.6 +/- 2.9 ng/ml, respectively). Evaluation of the area under the curve (AUC) also showed no difference in the GH response to GHRH, PD and PD + GHRH between the three groups studied. These results confirm that the combination PD + GHRH is a powerful test to study the GH secretory capacity of the pituitary, and show that pubertal maturation has no effect on the GH response to this test.