Insulin-like Growth Factor Binding Protein-3 (IGF BP-3) is a binding protein to Insulin-like Growth Factors that modulates IGF-1 actions impacting growth regulation. The test measures IGF BP-3 levels in blood using immunoassays and indicates growth hormone and IGF-1 activity. Healthcare providers suggest testing for assessing growth-related disorders, monitoring growth hormone therapy, and guiding treatment for abnormal growth patterns.