Factors Influencing the Growth Hormone Response to Growth Hormone-Releasing Hormone in Children with Idiopathic Growth Hormone Deficiency

Abstract

Objective: To evaluate the factors influencing the growth hormone (GH) response to GH-releasing hormone (GHRH) test in idiopathic GH deficiency. Methods: 28 patients aged 4.9 ± 0.7 years with certain GH deficiency were given GHRH (2 µg/kg). Results: The GH peak after GHRH was correlated negatively with age at evaluation (r = –0.37, p < 0.05) and body mass index (r = –0.44, p = 0.02), and positively with anterior pituitary height (r = 0.47, p = 0.02), GH peak after non-GHRH stimulation (r = 0.78, p < 0.0001) and spontaneous GH peak (r = 0.82, p = 0.007). It was lower in the patients aged >5 years than in the youngest (p = 0.04), but it was similar in the patients with and without features suggesting a hypothalamic origin. Conclusion: The GH response to GHRH test cannot be used to differentiate between hypothalamic and pituitary forms of idiopathic GH deficiency, probably because the GH response decreases after the first 5 years of life, whatever the origin of the deficiency.