Background: Growth hormone (GH) release is pulsatile, and daytime GH levels are low. GH stimulation tests are therefore needed in cases requiring GH level investigation. The purpose of this study was to compare the results of L-dopa and clonidine GH stimulation tests applied in children with short stature and to identify which of these tests should be primarily selected. Methods: The records of 68 patients aged between 2.5 and 16.6 years presenting to the pediatric endocrinology clinic with short stature and undergoing GH stimulation tests between September 2016 and February 2021 were evaluated retrospectively. Cases with GH levels <10 ng/dl following the first GH stimulation test then underwent the other GH stimulation test. Thirty-four (50%) of the cases in the study consisted of individuals beginning with the clonidine test, while the other 34 (50%) started with the L-dopa test. Results: Seventeen (50%) individuals in whom clonidine was employed in the first test had low GH responses, while a low GH response was determined at the second, L-dopa test, in 15 (88.2%) of these individuals, significant variation being observed between the groups (p< 0.001). Conclusion: GH stimulation tests performed to investigate GHD are laborious and time-consuming. The first stimulation test to be applied to differentiate GHD from ISS must therefore be well selected. The clonidine stimulation test, with higher sensitivity than but similar specificity to the L-dopa test, can be employed as the first test.
