IGF-1 (Insulin-like Growth Factor 1) Test
Reviewed
This test measures the amount of insulin-like growth factor 1 (IGF-1) in your blood. IGF-1 helps manage the effects of growth hormone and promotes normal growth of bones and tissues. The test is used to detect and monitor growth hormone disorders such as deficiency, insensitivity, gigantism, and acromegaly. Because IGF-1 levels are more stable than growth hormone levels, this test provides a reliable way to assess growth hormone status.
Preparation and collection
You don't need any special preparations for an IGF-1 test.
Understanding this test
Use the reference interval and units printed by the laboratory that performed the test. A result outside that interval is not a diagnosis by itself, and a result inside it does not rule out every condition. Your symptoms, history, medicines, timing, and related tests can change what the result means.
- IGF-1 levels change normally with age (low in childhood, peak during puberty, decrease in adulthood).
- Lower than normal levels may be due to growth hormone deficiency, growth hormone insensitivity, or normal age-related decline.
- Higher than normal levels may indicate gigantism (children) or acromegaly (adults), often from a pituitary tumor.
- Interpretation requires correlation with clinical findings and additional tests (e.g., GH stimulation/suppression test, IGFBP-3 test).
What to do next
Your healthcare provider will interpret the results in the context of your symptoms, age, and other tests. Further evaluation may include GH stimulation or suppression tests, IGFBP-3 test, or imaging to check for pituitary tumors.
Evidence source
U.S. National Library of Medicine: IGF-1 (Insulin-like Growth Factor 1) Test