What is Insulin-like growth factor 1 (IGF-1)?

The hepatic mediator of growth hormone's anabolic effects. Structurally it is Single-chain growth factor (70 aa).

How strong is the evidence for IGF-1?

PeptideHormone grades IGF-1 at the "Established" evidence tier — its mechanism and core effects are settled across the peer-reviewed literature. It is catalogued as an endogenous signal the body produces itself, and the tier is an editorial judgment about the public literature that can change as the science does.

What is the half-life of IGF-1?

The reported circulating half-life of IGF-1 is ~12–16 h bound to IGFBPs (~10 min free).

Insulin-like growth factor 1IGF-1

The hepatic mediator of growth hormone's anabolic effects.

EndogenousEstablishedCompare lineage

The messenger that does the growing while growth hormone takes the name — most signals in the body are relayed before they act.

Identity

Class: Single-chain growth factor (70 aa)
Source: Liver (GH-stimulated) and local tissues
Receptor: IGF-1 receptor (IGF-1R, a receptor tyrosine kinase)

Key properties

Evidence floorClinicalREF1CLIN1

Molecular weight

~7,649 Da

REF

Half-life (native)

~12–16 h bound to IGFBPs (~10 min free)

CLIN

Model dosing

Approximate values for the native hormone; engineered analogs are often deliberately larger and far longer-acting. Each figure carries its own provenance tier, and the floor is the weakest of them - the Standard.

Mechanism

GH stimulates hepatic IGF-1, which carries out much of GH's tissue-growth effect and feeds back negatively on the pituitary and hypothalamus to restrain further GH release. IGF-1 circulates bound to IGF-binding proteins that modulate its availability.

Reference notes

IGF-1 is the principal effector of GH's growth-promoting actions.
Its negative feedback is why sustained secretagogue exposure does not produce limitless GH.
IGF-binding proteins are a key layer controlling how much IGF-1 is bioavailable.

Common questions

What is Insulin-like growth factor 1 (IGF-1)?: The hepatic mediator of growth hormone's anabolic effects. Structurally it is Single-chain growth factor (70 aa).
How does IGF-1 work?: GH stimulates hepatic IGF-1, which carries out much of GH's tissue-growth effect and feeds back negatively on the pituitary and hypothalamus to restrain further GH release. IGF-1 circulates bound to IGF-binding proteins that modulate its availability.
How strong is the evidence for IGF-1?: PeptideHormone grades IGF-1 at the "Established" evidence tier — its mechanism and core effects are settled across the peer-reviewed literature. It is catalogued as an endogenous signal the body produces itself, and the tier is an editorial judgment about the public literature that can change as the science does.
What is the half-life of IGF-1?: The reported circulating half-life of IGF-1 is ~12–16 h bound to IGFBPs (~10 min free).

Selected literature

Curated peer-reviewed reviews, sourced from PubMed. Selected for relevance, not exhaustive — open any entry on PubMed for the full record and its primary citations.

1.Regulation and function of insulin and insulin-like growth factor receptor signalling · Nature reviews. Molecular cell biology, 2025 · PMID 39930003
2.Insulin-Like Growth Factor-1 and Neuroinflammation · Frontiers in aging neuroscience, 2017 · PMID 29163145

External references

IGF-1 in the public knowledge graph — the same entity resolved across the authoritative chemistry and protein databases.