IGF-1 is a protein made mainly by the liver in response to growth hormone. It circulates in the blood and drives much of that hormone's effect on tissues. You may have this test as a steadier stand-in for growth hormone. Its level changes little through the day, so a single draw is more reliable.

What is a normal Growth factor level range?

A typical adult range is around Strongly age- and sex-dependent; Adults (20–30 yrs): approximately 115–355 ng/mL; Adults (>60 yrs): approximately 55–205 ng/mL; children's ranges vary by pubertal stage. No India-specific national reference interval is published for this parameter; your lab's printed range is the most reliable comparison. Ranges vary by lab, method and equipment — the range printed on your own report is the one that applies to your result.

IGF-1 — What It Means in Your Blood Test

New to reading lab reports? Start with our guide to reading a blood test report

This is a growth signal the liver makes that carries out many of growth hormone's effects.

Your IGF-1 result offers a steadier window onto growth-related activity than a snapshot of the hormone behind it. Its calm, day-long level makes a single reading dependable.

Also known as: Insulin-like growth factor 1, Somatomedin C, IGF1, SM-C

Kept in balance

This isn't a case where higher or lower is better. Your body keeps it in a narrow band, and both directions can matter.

Last reviewed: 2026-08-16

What is IGF-1?

IGF-1 is a protein made mainly by the liver in response to growth hormone. It circulates in the blood and drives much of that hormone's effect on tissues.

Why is IGF-1 tested?

You may have this test as a steadier stand-in for growth hormone. Its level changes little through the day, so a single draw is more reliable.

What is a normal IGF-1 range?

India: No India-specific national reference interval is published for this parameter; your lab's printed range is the most reliable comparison.
Global: Strongly age- and sex-dependent; Adults (20–30 yrs): approximately 115–355 ng/mL; Adults (>60 yrs): approximately 55–205 ng/mL; children's ranges vary by pubertal stage

Ranges vary by lab, method and equipment — the range printed on your own report is the one that applies to your result.

Source: [Endocrine Society, 2014]

What does your IGF-1 value mean?

There is no widely-accepted set of value bands for this parameter. Compare your result with the reference range printed on your own report, and discuss it with your doctor.

What does a high IGF-1 result mean?

A high result can link to too much growth hormone and its effects on the body. Your doctor can help interpret it in your context.

What does a low IGF-1 result mean?

A low result can go with low growth hormone, poor nutrition, liver problems, or an underactive thyroid. This is worth discussing with your doctor.

What can affect your IGF-1 result?

Age (peaks in the teens, then falls)
Nutrition (drops when nutrition is poor)
Liver function (the main place it is made)
Thyroid status
Growth hormone or IGF-1 taken from an outside source

Questions to ask your doctor

About this result

What does my IGF-1 result mean for me specifically, given my age and health?
Is my IGF-1 in the range that is right for me, not just the lab's general range?

What to do next

Could anything I eat, do, or take have affected my Growth factor level result?
Is there anything I should do about my IGF-1, or is it fine to leave as it is?

About retesting

Does my IGF-1 need to be repeated, and if so, when?
The typical range for IGF-1 can vary between labs — should I compare my result against my own lab's printed range?

The bigger picture

Should my IGF-1 be looked at together with my Total Testosterone and Free Testosterone result?
Does my IGF-1 connect to any condition I already have, or to anything I have noticed in how I feel?

Frequently asked questions

What is IGF-1?: IGF-1 is a protein made mainly by the liver in response to growth hormone. It circulates in the blood and drives much of that hormone's effect on tissues. You may have this test as a steadier stand-in for growth hormone. Its level changes little through the day, so a single draw is more reliable.
What is a normal Growth factor level range?: A typical adult range is around Strongly age- and sex-dependent; Adults (20–30 yrs): approximately 115–355 ng/mL; Adults (>60 yrs): approximately 55–205 ng/mL; children's ranges vary by pubertal stage. No India-specific national reference interval is published for this parameter; your lab's printed range is the most reliable comparison. Ranges vary by lab, method and equipment — the range printed on your own report is the one that applies to your result.
What does a high IGF-1 result mean?: A high result can link to too much growth hormone and its effects on the body. Your doctor can help interpret it in your context.
What does a low IGF-1 result mean?: A low result can go with low growth hormone, poor nutrition, liver problems, or an underactive thyroid. This is worth discussing with your doctor.
What can affect your IGF-1 result?: Several everyday factors can influence it, including Age (peaks in the teens, then falls), Nutrition (drops when nutrition is poor), Liver function (the main place it is made), Thyroid status, Growth hormone or IGF-1 taken from an outside source.

Sources

Endocrine Society (2014) — Acromegaly: An Endocrine Society Clinical Practice Guideline
Growth Hormone Research Society (2018) — Consensus guidelines for the diagnosis and treatment of growth hormone deficiency

Part of the Hormones

See the full Hormones guide

Related tests in this panel

Check your IGF-1

Upload your report to see your IGF-1 explained for you.

Upload your report