What does IGF-1 measure and what does it indicate?
IGF-1 (insulin-like growth factor 1) is the primary downstream effector of growth hormone and the most stable marker of growth-hormone status. It is read in growth-hormone evaluation, peptide secretagogue review, and in longevity contexts where the IGF-1 / longevity tradeoff is discussed.
Full answer
IGF-1 (insulin-like growth factor 1) is produced mainly by the liver in response to growth hormone (GH) and is the most stable, routinely available marker of GH status. Because GH itself is pulsatile and short-lived in serum, IGF-1 is the practical metric. It is used to evaluate growth-hormone deficiency, to monitor peptide secretagogues (sermorelin, ipamorelin) when these are provider-reviewed and appropriate, and to inform longevity discussions where the tradeoff between body composition / recovery benefits and the IGF-1 / longevity association is weighed individually. Interpretation requires age- and sex-specific reference ranges; what is high for a 60-year-old is mid-range for a 25-year-old. IGF-1 is never read in isolation from clinical context.
Educational. Not a substitute for individualized provider review.
- IGF-1 — Primary source · oMeds
- Reviewed by Dr. Laura Purdy, MD, MBA · Clinical Director, oMeds · Last reviewed 2026-05-29