Understanding IGF-1
IGF-1 is a marker commonly reviewed in growth-axis, metabolic, and hormone-related lab panels. It provides growth-axis context and is usually read alongside metabolic markers, hormone markers, and body-composition tracking, because each captures a different part of the picture. This page explains, in plain language, what IGF-1 is, why it is commonly measured, and how it fits alongside the other markers.
Everything here is educational context. It does not interpret what any particular value means, does not diagnose, and does not describe any course of action.
What IGF-1 is
- IGF-1 stands for insulin-like growth factor 1.
- IGF-1 is involved in growth-hormone (GH) signaling — it is the main mediator of GH, and most circulating IGF-1 is produced by the liver.
- IGF-1 is commonly discussed alongside growth hormone because it is more stable through the day and can reflect longer-term GH-axis activity better than a single GH measurement.
- IGF-1 provides growth-axis context — one part of the picture, not a full picture by itself.
IGF-1 is one marker among several. This page describes what it is and why it is measured; it does not describe any value as good or bad and does not interpret an individual result.
Why IGF-1 is commonly measured
IGF-1 is commonly measured as part of a broader look at the growth axis and overall status. In research and clinical education it adds context in several ways:
- Growth-axis context — IGF-1 reflects GH-axis activity over a longer window than a single GH reading.
- Hormone-related tracking — it is read alongside other hormone markers.
- Metabolic research context — IGF-1 is referenced in metabolic literature.
- Body-composition research context — it is discussed alongside body-composition markers.
- Age, sex, assay, and lab-specific ranges — IGF-1 is read within the context of these factors.
This page does not interpret what any particular value means and does not recommend any action. Any individual measurement should be discussed with a licensed healthcare provider.
Relationship to metabolic and hormone biomarkers
IGF-1 is most useful when read alongside the other markers, because each describes a different part of the picture. On the metabolic side:
- HbA1c reflects longer-term glucose exposure.
- Fasting Glucose reflects glucose at one point in time.
- Fasting Insulin provides insulin-response context.
- ApoB provides lipid / atherogenic-particle context.
- hs-CRP provides inflammatory context.
- Cortisol can provide adrenal-related context.
- IGF-1 provides growth-axis context.
On the hormone side, IGF-1 is also read alongside the sex hormone markers, which provide hormone-axis context:
- Total Testosterone and Free Testosterone describe total and unbound testosterone.
- SHBG provides binding context.
- LH and FSH provide pituitary-gonadal signaling context.
- DHEA-S provides adrenal androgen-related context.
- Estradiol provides estrogen-related context.
Beyond lab markers, body weight, height, body composition, and muscle-progress metrics can add physical-progress context when trends are organized together in the Pepvela app. These markers can be reviewed together for educational tracking, but each measures something different.
Common units
IGF-1 is reported in more than one unit:
- ng/mL (nanograms per milliliter) — commonly used in the United States.
- nmol/L (nanomoles per liter) — an SI unit common in many other countries.
Units and assay methods vary by laboratory and by country, so always read the unit printed next to your own measurement.
Reference ranges are strongly age-dependent
This page does not publish a single numeric IGF-1 range, because IGF-1 is read differently depending on age and the specific assay.
IGF-1 reference ranges are strongly age-dependent and may vary by sex, assay, laboratory, and population. A single public number does not apply to all users. Where a measurement is available, Pepvela prioritizes the reference range printed on your own lab report.
Context notes
IGF-1 is usually interpreted together with age, the assay used, the laboratory's own range, and other clinical context. Because IGF-1 changes across life stages and differs between assays, a value is read within the context of the individual and the specific laboratory performing the measurement rather than against a single fixed number.
For this reason, IGF-1 is commonly reviewed alongside other markers and the reference interval provided on the lab report.
Related biomarkers
These related biomarkers are often reviewed alongside IGF-1 for educational context:
Metabolic markers
Hormone markers
Related peptide research
Research literature involving certain compounds may measure growth-axis, metabolic, hormone-related, inflammatory, or body-composition-related markers as endpoints. The following research pages are provided for educational context only and make no claim about any effect on IGF-1 or growth hormone:
Citations
- MedlinePlus. IGF-1 (Insulin-like Growth Factor 1) Test. U.S. National Library of Medicine. https://medlineplus.gov/lab-tests/igf-1-insulin-like-growth-factor-1-test/
- Bailes J, Soloviev M. Insulin-Like Growth Factor-1 (IGF-1) and Its Monitoring in Medical Diagnostic and in Sports. Biomolecules. 2021;11(2):217. https://pmc.ncbi.nlm.nih.gov/articles/PMC7913862/