Glossary
IGF-1
Insulin-Like Growth Factor 1 — a hormone produced primarily by the liver in response to growth hormone, mediating most of GH's anabolic and tissue-repair effects.
Also known as:
Insulin-Like Growth Factor 1 IGF-1 LR3 somatomedin C
IGF-1 is the primary downstream mediator of growth hormone’s effects — when GH binds to liver receptors, the liver produces and releases IGF-1 into circulation. IGF-1 then acts on muscle, bone, connective tissue, and other organs to promote growth, protein synthesis, and cellular repair.
Serum IGF-1 levels are commonly used as a proxy biomarker for GH axis activity — if a GHRH/GHRP stack is working, IGF-1 levels should rise. Synthetic IGF-1 analogs like IGF-1 LR3 (a long-acting variant) are also used as standalone research compounds, bypassing the GH axis entirely.