Use

Insulin‑like growth factor binding proteins bind IGF‑I and IGF‑II with high affinity but do not bind insulin. IGFBP‑3 is the major carrier of the IGFs, transporting approximately 95% of circulating IGF‑I and IGF‑II. It is growth hormone‑responsive—levels are high in acromegaly and low in hypopituitarism, and increase in GH‑deficient children after GH administration. The assay is useful in assessing GH action (e.g., IGF‑I/IGFBP‑2 and IGFBP‑2/IGFBP‑3 ratios) and discriminating GH deficiency versus other causes of short stature, and in assessing nutritional status, as IGFBP‑3 decreases during caloric and protein restriction.