Mark L. Hartman, Arthur Weltman, Anthony Zagar, Rebecca L. Qualy, Andrew R.
Hoffman, and George R. Merriam
Growth Hormone Replacement Therapy in Adults
with Growth Hormone Deficiency Improves Maximal Oxygen Consumption Independently
of Dosing Regimen or Physical Activity
J. Clin. Endocrinol. Metab., Jan 2008;
93: 125 - 130.
The purpose of this study was to determine whether
improvements in aerobic exercise capacity with growth hormone (GH) treatment in
adults with growth hormone deficiency (GHD) are related to changes in physical
activity or affected by the GH dosing regimen. Several studies have demonstrated
an improvement in aerobic exercise capacity with six months of GH replacement in
adults with GH deficiency (GHD).
The study was conducted at five
academic medical centers with exercise physiology laboratories. The study
included 29 participants with GHD due to hypothalamic-pituitary disease. The
participants received GH replacement therapy, administered either as a fixed
body weight-based dosing regimen as an individualized dose titration regimen for
32 weeks. The study measured maximal oxygen consumption, oxygen consumption at
the lactate threshold, oxygen consumption at the ventilatory threshold, and
weekly energy expenditure, assessed at baseline and end point.
Maximal
oxygen consumption increased significantly from baseline to end point in the
group as a whole. The changes were greater in the individualized dose titration
regimen group. Oxygen consumption at the lactate threshold, oxygen consumption
at the ventilatory threshold, and weekly energy expenditure did not change.
Growth Hormone replacement therapy in GH-deficient adults improved maximal
oxygen consumption similarly with both dosing regimens, without any influence of
physical activity. There was no effect on submaximal exercise performance.
