IGF-1
A growth factor made mainly by the liver in response to growth hormone; a stable marker of growth hormone activity.
| Typical reference range | 80–300 ng/mL |
Ranges vary by laboratory, method, age and sex: always use the range printed on your own report. Why labs differ.
What it measures
Growth hormone is released in pulses by the pituitary, mostly during sleep, and stimulates the liver to produce IGF-1, which mediates many of its effects on tissue growth, muscle and bone. IGF-1 is stable throughout the day.
Why it matters
IGF-1 screens for growth hormone excess (acromegaly) and deficiency, and monitors their treatment. In longevity research, both very low and very high levels are associated with adverse outcomes.
What a high result can mean
High levels occur with acromegaly (growth hormone-secreting pituitary tumor), growth hormone or peptide (secretagogue) use, puberty, pregnancy and high protein intake.
What a low result can mean
Low levels occur with growth hormone deficiency, aging, malnutrition or low protein/calorie intake, liver disease, hypothyroidism, poorly controlled diabetes, oral estrogen and chronic illness.
What affects the result
Highly age-dependent: levels peak in adolescence and decline steadily, so lab ranges are age-specific (the range shown approximates ages 30-50). Protein and calorie intake affect it. Assays differ, so compare within the same lab.
Units and conversion
Usually reported in ng/mL.
- From nmol/L: multiply by 7.65 to get ng/mL
- From ug/L: multiply by 1 to get ng/mL
Also called on lab reports
IGF-I, Insulin-Like Growth Factor 1, Insulin-Like Growth Factor I, Somatomedin C, IGF 1, IGF-1, LC/MS, Somatomedin-C
Related tests: Adrenal & Pituitary
This page is educational and does not replace advice from a healthcare professional.