Adult growth hormone replacement: current understanding.

Area of Science:

• Endocrinology
• Metabolic Research
• Pharmacology

Background:

• Adult growth hormone (GH) replacement initially used pediatric dosing, leading to pharmacological rather than physiological effects.
• Weight-based dosing in adults resulted in lower doses for females, explaining observed gender-based efficacy differences in GH replacement studies.
• Females require threefold greater GH secretion than males to maintain similar insulin-like growth factor-I (IGF-I) levels.

Purpose of the Study:

• To evaluate the efficacy and safety of individualized growth hormone (GH) replacement therapy in adults.
• To compare the effects of individualized GH dosing with traditional weight-based regimens.
• To assess gender-specific responses to GH replacement therapy.

Main Methods:

• Review of studies employing weight- and surface area-based GH dosing in adults.
• Analysis of recent studies utilizing individualized GH doses to normalize serum insulin-like growth factor-I (IGF-I) levels.
• Examination of the impact of GH replacement on bone mineral content, vascular risk markers, and endothelial dysfunction.

Main Results:

• Individualized GH dosing normalizes serum IGF-I levels and shows beneficial effects comparable to, but less pronounced than, earlier weight-based studies.
• Individualized GH dosing demonstrates equal efficacy between genders for most biological endpoints.
• GH replacement positively influences vascular risk markers and endothelial dysfunction, with effects maintained long-term (5-10 years).

Conclusions:

• Individualized GH dosing is effective and achieves gender equity in treatment response.
• GH replacement therapy demonstrates long-term benefits and improves surrogate markers of vascular health.
• Further research is needed on depot GH preparations and long-term mortality effects.