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What It Is

Insulin-like growth factor binding protein 3 (IGFBP-3) is the main carrier of somatomedin C (also called insulin-like growth factor-1, or IGF-1) in the body. Blood levels of both these proteins are controlled by human growth hormone (hGH), a hormone that's produced by the pituitary gland, a pea-sized gland in the brain that works with the endocrine system. The pituitary gland regulates growth and the function of other glands.

But IGFBP-3 is more than just a transporter. It also helps extend the life of somatomedin C in the blood and helps control its effects on body tissues.

Levels of IGFBP-3 are highest during childhood and puberty, then they decrease during adulthood. Levels also may be affected by sexual maturation and nutritional status.

Why It's Done

The main reason doctors order the IGFBP-3 test is for its usefulness as an indicator of whether someone is producing a normal amount of human growth hormone. In this way, the IGFBP-3 test is used to check for pituitary gland disorders and abnormalities in growth hormone production.

Symptoms such as short stature or excessive growth (gigantism) may warrant an IGFBP-3 test. The test also might be used to monitor treatment of growth disorders.



The Procedure




What to Expect

Collecting a sample of blood for the test is only temporarily uncomfortable and can feel like a quick pinprick. Afterward, there may be some mild bruising, which should go away in a few days.

Getting the Results

The blood sample will be processed by a machine, and the results are commonly available after a few days.


The IGFBP-3 test is considered a safe procedure. However, as with many medical tests, some problems can occur with having blood drawn, such as:

  • fainting or feeling lightheaded
  • pain associated with multiple punctures to locate a vein

Helping Your Child



If You Have Questions

If you have questions about the IGFBP-3 test, speak with your doctor.