Is my IGF-1 (Insulin-Like Growth Factor 1) normal?
Free blood test checker · Standard + longevity-optimal ranges
What is a normal IGF-1 level?
IGF-1 is the primary mediator of growth hormone (GH) effects and reflects overall GH status. Normal range is 100-300 ng/mL (age-dependent). IGF-1 presents a longevity paradox: too much accelerates cancer risk and cellular aging via mTOR pathway activation and unchecked cell proliferation, while too little causes frailty, sarcopenia, and cognitive decline. Longevity researchers recommend targeting a middle-to-lower optimal range of 120-180 ng/mL rather than pushing maximally high — enough for tissue maintenance without fueling accelerated aging.
| Range | Values |
|---|---|
| Standard Reference | 100–300 ng/mL |
| Longevity Optimal | 120–180 ng/mL |
| Low Risk | < 50 ng/mL |
What causes abnormal IGF-1 levels?
Elevated IGF-1 is caused by acromegaly (GH-secreting pituitary adenoma), obesity (insulin and IGF-1 are closely linked), high-protein diets, and exogenous GH or IGF-1 use. Low IGF-1 is caused by GH deficiency, liver disease, malnutrition, hypothyroidism, chronic illness, and advanced age. Certain medications like estrogen (oral contraceptives) can lower IGF-1.
When should you see a doctor?
See your doctor if IGF-1 is below 50 ng/mL (especially with symptoms of GH deficiency: fatigue, muscle loss, poor bone density) or above 350 ng/mL (which may indicate acromegaly). Changes in shoe or ring size, jaw enlargement, or excessive sweating with high IGF-1 warrant urgent evaluation.
IGF-1 and longevity
IGF-1 sits at the center of the longevity debate. The GH/IGF-1 axis is one of the most conserved aging pathways across species — reducing it extends lifespan in worms, flies, and mice. Laron syndrome patients (GH receptor deficiency, very low IGF-1) have near-zero cancer rates and apparent protection from diabetes. However, human observational studies show a U-shaped mortality curve: both very low and very high IGF-1 are associated with increased all-cause mortality. The emerging consensus among longevity clinicians is to maintain IGF-1 in the lower-normal range for your age — enough for muscle maintenance and cognitive function, but not so high as to promote unchecked cellular growth.
Where to get a IGF-1 test
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Related biomarkers
These biomarkers are often tested alongside IGF-1 for a more complete picture.
Frequently asked questions
What is a normal IGF-1 level?
Is high IGF-1 good or bad for longevity?
What causes low IGF-1?
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Sources: Reference ranges based on AHA/ACC, ADA, and AACE clinical guidelines. Biological variation data from Ricos/Westgard database. Longevity-optimal ranges reflect targets used by preventive and functional medicine practitioners.
Last reviewed: April 2026. This tool provides general health information and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult your healthcare provider about your specific results.