IGF-1 in Blood Tests: What Your Levels Mean
IGF-1 reflects how much growth hormone your body produces. Learn what an IGF-1 test measures and what high or low levels may indicate for your health.
What is IGF-1?
Insulin-like Growth Factor 1 (IGF-1) is a hormone produced mainly by the liver in response to growth hormone released by the pituitary gland. It carries out many of growth hormone’s effects, promoting growth in childhood and supporting tissue repair, muscle maintenance, and metabolism throughout life. Because IGF-1 stays relatively stable across the day while growth hormone rises and falls in bursts, it is used as a practical marker of average growth hormone activity.
What does it assess?
An IGF-1 test reflects how much growth hormone the body is producing over time. It is used to help evaluate suspected growth hormone deficiency or excess, to assess growth problems in children, and to monitor conditions such as acromegaly. Results are interpreted against age and sex, because IGF-1 is naturally highest during puberty and declines steadily with age.
How do I optimize my IGF-1 levels?
IGF-1 is influenced by adequate protein intake, regular resistance and aerobic exercise, and good quality sleep, since much of the body’s growth hormone is released during deep sleep. Chronic undernutrition, very low calorie intake, and poorly controlled illness can lower IGF-1, so addressing those supports healthier levels. Because both unusually high and unusually low IGF-1 carry health risks, the goal is a level appropriate for your age rather than pushing it as high as possible, and persistent abnormal results should be evaluated by a clinician.
What do high and low IGF-1 levels mean?
High IGF-1 levels can reflect excess growth hormone, most notably in acromegaly, where ongoing overproduction enlarges bones and soft tissues and raises the risk of metabolic and cardiovascular problems. Low IGF-1 levels can indicate growth hormone deficiency, which in children can impair growth and in adults may contribute to reduced muscle mass, low energy, and changes in body composition. Levels can also be lowered by malnutrition, liver disease, and poorly controlled diabetes, so results are always read in the context of overall health.
For a full breakdown of IGF-1 test prices across labs, see the IGF-1 test cost comparison.
References
[1] Yuen KCJ, Hjortebjerg R, Ganeshalingam AA, Clemmons DR, et al. Growth hormone/insulin-like growth factor I axis in health and disease states: an update on the role of intra-portal insulin. Front Endocrinol (Lausanne). 2024;15:1456195. PMID: 39665021
[2] Juul A, Bang P, Hertel NT, Main K, et al. Serum insulin-like growth factor-I in 1030 healthy children, adolescents, and adults: relation to age, sex, stage of puberty, testicular size, and body mass index. J Clin Endocrinol Metab. 1994;78(3):744-52. PMID: 8126152
[3] Junnila RK, Strasburger CJ, Bidlingmaier M. Pitfalls of insulin-like growth factor-i and growth hormone assays. Endocrinol Metab Clin North Am. 2015;44(1):27-34. PMID: 25732639
