The IGF Binding Protein 3 (IGFBP 3) test contains 1 test with 1 biomarker.
Insulin-like growth factor binding proteins bind IGF-I and IGF-II with high affinity but do not bind insulin. Of the six distinct IGF binding proteins structurally characterized at this time, IGFBP-3 has been shown to be the major carrier of the IGFs, transporting approximately 95% of circulating IGF-I and IGF-II.
IGFBP-3 is growth hormone (GH) responsive. Thus, levels are high in cromegaly and low in hypopituitarism, and levels increase in GH-deficient children after GH administration. Thus, both assays and the ratios of IGF-I/IGFBP-2 and IGFBP-2/IGFBP-3 are useful as markers of GH action and for discriminating between growth hormone deficiency and short stature due to other etiologies in children. Other causes of short stature that result in reduced IGFBP-3 levels include poorly controlled diabetes.
The IGFBP-3 assay is useful in assessing nutritional status, since IGFBP-3 decreases during both caloric and protein restriction