: Insulin-like Growth Factor I (IGF-I) [Somatomedin C], Serum/Plasma, Mass Concentration, Immunoassay
: This test measures the level of insulin-like growth factor 1 (IGF-I), a hormone produced mainly by the liver in response to growth hormone, using a serum or plasma sample analyzed by immunoassay.
[": An IGF-I measurement helps assess growth hormone activity and is commonly used to evaluate growth disorders and pituitary conditions."]
Key facts at a glance
- LOINC
- 60012-2
- Short code
- IGF-I sp1 p chal SerPl-mCnc
- Synonyms
- IGF-I sp1 p chal SerPl-mCnc
- Category
- hormone
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
: What Is IGF-I?
: IGF-I, also called somatomedin C, is a hormone that mediates many of the growth-promoting effects of growth hormone. It is produced primarily in the liver and circulates in the blood, where its level tends to remain relatively stable throughout the day compared with growth hormone itself.
: Why This Test Is Ordered
: Doctors order an IGF-I test to help evaluate growth hormone production and activity. It is often used when there is concern about growth hormone deficiency or excess, such as in children with growth problems or adults with symptoms suggesting acromegaly. It may also be used to monitor response to treatment.
: How the Sample Is Collected
: A blood sample is drawn from a vein, most commonly from the arm, into a tube that yields serum or plasma. No special preparation is usually required, though your healthcare provider will tell you if fasting or timing of the draw matters for your situation.
: How to Interpret Results
: IGF-I levels are interpreted in the context of your age and sex, because normal levels vary across life stages. Results outside the expected range may prompt further testing, such as growth hormone stimulation or suppression tests. Your care team will explain what your result means for you.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
: IGF-I is a key marker of growth hormone activity; abnormal levels can point to growth hormone deficiency, growth hormone excess such as acromegaly, or other endocrine and nutritional conditions. Because reference ranges depend on age and sex and vary by laboratory method, results should be interpreted by a qualified clinician alongside symptoms and other tests.
Short name
: IGF-I
Frequently asked questions
: Does an abnormal IGF-I result always mean I have a hormone disorder?
: Do I need to fast before an IGF-I blood test?
: Can I take this test at any time of day?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy