Insulin-like growth factor-I

Insulin-like growth factor-I (IGF-1) is a hormone produced by the liver in response to growth hormone, mediating growth hormone's effects on growth and metabolism. An IGF-1 test screens for growth hormone disorders. Low IGF-1 suggests growth hormone deficiency, causing short stature in children or reduced muscle mass, strength, and metabolic dysfunction in adults. High IGF-1 may indicate excess growth hormone (acromegaly or gigantism), causing enlarged extremities and organs. Normal ranges vary widely by age, sex, and puberty stage, complicating interpretation. IGF-1 is useful for screening, though diagnosis requires additional testing and dynamic assessment.