A Comparison of L-Dopa and Clonidine Growth Hormone Stimulation Tests in
Children with Short Stature
Abstract
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.