IGF-1 (Insulin-like Growth Factor 1)

Hormones

Growth & Repair

IGF-1 (Insulin-like Growth Factor 1) mediates most of the anabolic, regenerative effects of growth hormone, supporting tissue repair, muscle maintenance, and healing. It is largely produced in the liver in response to growth hormone signaling. Longevity practices track it because its relationship to aging is genuinely nuanced, with both too little and too much carrying trade-offs.

What It Measures

Mediator of growth hormone effects; anabolic, regenerative; longevity debates (moderate levels may be optimal)

Optimal vs. Lab Range

Longevity Optimal

150–225 ng/mL (middle-aged)

Target range for optimal health and longevity based on research.

Standard Lab

115–355 ng/mL (age-dependent)

Population-based reference range from standard labs.

Why It Matters

IGF-1 illustrates one of the more debated relationships in longevity, where the goal is often a moderate, middle-of-range level rather than a maximum. Low IGF-1 is associated with growth hormone deficiency, aging, malnutrition, muscle wasting, poor wound healing, and cognitive decline, all of which undermine healthspan. Very high levels, however, promote cell proliferation and are linked to acromegaly and increased cancer risk. This U-shaped pattern means the aim is balance: enough to preserve muscle, repair, and vitality, without pushing into the range where excess growth signaling becomes a liability. It is best interpreted alongside growth hormone, IGFBP-3, and metabolic markers.

When Low

GH deficiency, aging, malnutrition, liver disease, muscle wasting, poor wound healing, cognitive decline

When High

Acromegaly, GH excess, cancer risk (very high levels promote cell proliferation)

How to Optimize

Because moderate levels are often optimal, foundational strategies favor healthy signaling without excess: regular resistance training, adequate dietary protein, and quality sleep all support IGF-1 naturally. Growth hormone secretagogues are considered only under physician direction and careful monitoring, given the concerns tied to very high levels. Where IGF-1 is elevated, evaluation rather than augmentation is warranted. Hormone testing and treatment must be individualized with your physician; this content is educational and not a substitute for medical advice.

Key Interventions & Linked Compounds

Moderate evidence

Key Interventions

Exercise (resistance training)

adequate protein

sleep

GH secretagogues (clinical)

Linked Compounds & Supplements

Colostrum

GABA

L-arginine

L-ornithine

MK-677 (clinical)

Curated from clinical literature. Individual results vary; consult a qualified clinician before changing a protocol.

Ordering Notes

Specimen

Serum; saliva for diurnal cortisol panels

Patient prep

No fasting required. Maintain usual diet and medications unless advised.

Recommended cadence

Semi-annual

Reporting unit

Confirm with the performing lab — units vary by region.

Pre-analytic notes

Standardize draw time of day, hydration, and recent exercise. Note any acute illness, supplements, or hormonal therapies on the requisition.

Recommended Follow-Up Actions

1
Confirm the result is reliable
Repeat abnormal values before acting — preferably from the same lab, same time of day, and under consistent prep. Rule out acute illness, recent intense exercise, or medication effects that can shift IGF-1 (Insulin-like Growth Factor 1).
2
Compare against optimal, not just lab range
Use the optimal window above as the target. Lab "normal" is built from the general population and often misses early dysfunction.
3
Pair with related markers
Order a complementary panel covering metabolic, inflammatory, and hormonal context to interpret this marker properly.
4
Discuss interventions with a clinician
Use the interpretation guidance above to frame the conversation. Bring trends, not just one datapoint, to your visit.
5
Re-test on a defined cadence
If a change is implemented, re-measure in 8–12 weeks for fast-moving markers, or 3–6 months for slower ones, to confirm response before escalating.