What is igf1

What is IGF-1

IGF-1, or Insulin-like Growth Factor 1, is a peptide hormone that functions as a key regulator of growth and metabolism in humans and other vertebrates. Produced primarily by the liver in response to growth hormone stimulation, IGF-1 circulates throughout the bloodstream and interacts with virtually every tissue in the body. It earned its name because its molecular structure and some functions resemble insulin, though it operates through different mechanisms.

The Growth Hormone-IGF-1 Axis

Growth hormone (GH) stimulates the liver to produce and release IGF-1, creating an interconnected system known as the somatotropic axis. This relationship is essential for normal growth during childhood and adolescence. As growth hormone pulses through the bloodstream, especially during sleep and exercise, it triggers IGF-1 production. Together, these hormones orchestrate bone lengthening, muscle protein synthesis, and increased metabolic rate.

IGF-1 Functions

IGF-1 promotes anabolic processes—building up muscle and bone tissue. It increases amino acid uptake in muscles, stimulates bone growth, and supports tissue repair. Beyond growth, IGF-1 influences metabolism, glucose regulation, and immune function. It also acts as a survival signal in cells, helping prevent cell death and supporting tissue maintenance throughout life.

IGF-1 Across the Lifespan

IGF-1 levels are highest during adolescence and early adulthood, coinciding with peak growth velocity and strength development. Levels gradually decline starting in the third or fourth decade of life at approximately 10-15% per decade. This decline contributes to age-related decreases in muscle mass (sarcopenia), bone density loss, and reduced metabolic rate in older adults.

Medical and Health Significance

Abnormally low IGF-1 levels can result in growth disorders and delayed development in children. In adults, deficiency is associated with reduced quality of life and metabolic dysfunction. Conversely, chronically elevated IGF-1 levels have been linked to increased cancer risk in some studies, highlighting the importance of maintaining physiologically appropriate levels. Clinically, IGF-1 measurements help diagnose growth hormone disorders and guide treatment decisions.