Sermorelin stimulates the pituitary to produce endogenous GH. Exogenous HGH replaces it entirely. The distinction — axis-preserving versus axis-bypassing — has profound implications for pulsatility, feedback regulation, safety, and long-term pituitary function.
The Fundamental Distinction: Stimulating vs Replacing
Sermorelin is a GHRH analogue: it binds the GHRH receptor on pituitary somatotrophs and stimulates the pituitary to produce and release the body's own growth hormone. Exogenous HGH bypasses this system entirely.
Mechanistic Pathway Comparison
Axis-preserving (sermorelin): works with the body's own regulatory systems, maintains somatostatin feedback, preserves pulsatile release pattern. Axis-bypassing (HGH): replaces endogenous production, suppresses natural GH secretion with chronic use.
Head-to-Head Comparison
A full attribute-by-attribute comparison across mechanism, pharmacokinetics, safety profile, regulatory status, cost, and research applications.