Insulin-like Growth Factor Binding Protein 3 (IGFBP-3) (often written as IGF-BP3 or IGFBP-3) is a blood test that measures the level of the main carrier protein for insulin-like growth factor (IGF-1) in the bloodstream.

IGFBP-3 is the most abundant binding protein for IGF in the blood. It binds to IGF-1 and IGF-2 and controls how much of these growth factors are “available” to act on body tissues. Because of this, it plays an important role in regulating growth, metabolism, and cell development.