What is IGF-1?
IGF-1 (Insulin-like Growth Factor-1) is a peptide hormone produced primarily by the liver in response to growth hormone (GH) signaling. When the pituitary gland releases GH, it travels to the liver and triggers IGF-1 production , making IGF-1 the downstream marker that reflects GH activity over time. Unlike GH itself, which fluctuates dramatically throughout the day in pulses, IGF-1 remains relatively stable in the bloodstream, making it the preferred clinical measurement of GH axis function.
IGF-1 is the single most important monitoring marker for any GH secretagogue research protocol. Whether researching Ipamorelin, CJC-1295, Sermorelin, Tesamorelin, or Hexarelin , IGF-1 must be established as a baseline before any protocol begins and monitored throughout. Elevated IGF-1 before a protocol starts may indicate the GH axis is already active and warrants caution. Low IGF-1 in the context of GH deficiency symptoms provides research context for why GH secretagogue protocols are studied.
What do the numbers mean?
Lab reference ranges vary by laboratory, age, sex, and testing method. Always interpret your results with your healthcare provider , do not self-diagnose based on these ranges.
Why this marker matters before peptide research.
IGF-1 is the primary outcome marker in nearly every GH secretagogue research study , it is what researchers measure to confirm a GH-stimulating compound is producing its intended biological effect. Protocols that elevate IGF-1 significantly above the optimal range may increase risk of side effects associated with GH excess. Protocols that fail to move IGF-1 within 8–12 weeks suggest the compound is not producing meaningful GH axis stimulation at the doses studied.
IGF-1 also has direct anabolic effects , it promotes protein synthesis, fat metabolism, and cellular repair , making it a relevant marker not just for monitoring but for understanding why GH secretagogues produce the body composition effects observed in research. IGF-1 interacts directly with insulin signaling, which is why baseline metabolic markers (fasting insulin, fasting glucose) are also relevant context before initiating GH secretagogue protocols.
From a safety perspective, pre-protocol IGF-1 elevation warrants careful evaluation. Some individuals have naturally elevated IGF-1 without exogenous GH use , starting a GH secretagogue protocol in this context risks pushing IGF-1 into ranges associated with adverse outcomes in epidemiological research. Establishing a true baseline before any protocol is non-negotiable from a research integrity standpoint.
How to get this test.
Where to order
Standard blood draw at any major lab , LabCorp, Quest Diagnostics, or through your physician. Also available through direct-to-consumer testing services such as Ulta Lab Tests and LabCorp OnDemand without a doctor's order.
How to prepare
No fasting required. Draw in the morning for most consistent results. Avoid intense exercise 24 hours before testing , acute exercise transiently elevates GH and IGF-1 and may produce an artificially elevated baseline reading.
What to ask for
"IGF-1" or "Insulin-like Growth Factor-1" , a straightforward, widely available test at all major labs. No special panel required. Order alongside testosterone and cortisol for a more complete GH axis picture.