IGF-1 (Insulin Like Growth Factor)

IGF-1 is produced in response to growth hormones released by the pituitary gland. Therefore, IGF-1 levels highly correlate with the "average" circulating levels of growth hormone in the blood. However, IGF-1 levels are more constant than growth hormone levels because IGF-1 has a longer half-life. Because of this the IGF-1 test is commonly regarded as the best way to measure human growth hormone (HGH) levels and activity.

Human growth hormone level abnormalities during childhood can cause a child to grow larger than normal or to grow less than normal. High levels of human growth hormone in adults can cause the bones of the face, jaw, hands and feet to grow larger than normal.

Human growth hormone therapies have been the focus controversies for many years. Human growth hormone replacement therapy is now prescribed as an anti-aging treatment and for a variety of other reasons. Human growth hormone therapies in healthy individuals have been found to provide some benefits such as an increase in muscle mass but with frequently reported side-effects.