Comparison of growth hormone stimulation tests in prepubertal children with short stature according to response to growth hormone replacement

Growth hormone (GH) stimulation tests are essential tools for diagnosing GH deficiency (GHD). We aimed to compare L-dopa, insulin, and arginine-induced stimulation tests based on response to GH replacement. We retrospectively collected data from a review of patients who underwent the GH stimulation test. A total of 138 patients diagnosed with idiopathic short stature were categorized into group I. The remaining 135 patients, who were diagnosed with GHD and treated for 1 year, were classified into 2 subgroups: group IIa, consisting of patients with an increase of at least 0.5 in height standard deviation score (SDS), and group IIb, patients with an increase of less than 0.5 in height SDS. At the initial visit, group IIa exhibited significantly lower insulin-like growth factor binding protein-3 (IGF-BP3) and higher body mass index (BMI) SDS compared to the other groups. Following 1 year of treatment, group IIb showed significantly lower height SDS, height SDS gain, growth velocity, predicted adult height SDS, weight SDS, and a higher insulin-like growth factor-1 SDS than group IIa. Bone age and IGF-BP3 were inversely associated, and BMI SDS and IGF-BP3 were positively associated with height SDS gain in GHD patients. The specificity and accuracy rates were 50.3% and 70.3% for the L-dopa-induced stimulation test, 72.3% and 86.6% for the insulin tolerance test (ITT), and 64.7% and 87.2% for the arginine-induced stimulation test (ArST). The ArST demonstrated lower specificity compared to the ITT. However, patients undergoing ArST experienced fewer side effects, suggesting that a careful selection of stimulation tests is crucial in diagnosing GHD.