What is the Origin of IGF-1/IGFBP-3 Molar Ratio?

This clinical and biochemical term stems from the intricate understanding of the Growth Hormone/IGF-1 axis, recognizing that the biological action of IGF-1 is heavily regulated by a family of binding proteins. The molar ratio offers a more dynamic assessment of the system than measuring the individual components in isolation.

What is the Mechanism of IGF-1/IGFBP-3 Molar Ratio?

IGFBP-3 binds the majority of circulating IGF-1, forming a large ternary complex that prolongs the half-life of IGF-1 and prevents its rapid extravasation. A lower molar ratio suggests a higher proportion of IGF-1 is bound and less is available to interact with its receptor to mediate its anabolic and metabolic effects. Conversely, an elevated ratio may indicate a state of increased IGF-1 bioactivity, which can be relevant in conditions like acromegaly or certain metabolic disorders.

IGF-1/IGFBP-3 Molar Ratio

Meaning

The IGF-1/IGFBP-3 Molar Ratio represents the relationship between Insulin-like Growth Factor-1 (IGF-1), a primary mediator of growth hormone action, and its principal binding protein, Insulin-like Growth Factor Binding Protein-3 (IGFBP-3). Calculating this ratio provides a clinical estimate of the bioavailability of IGF-1, the fraction that is unbound or loosely bound and therefore biologically active. This metric is used in endocrinology to assess growth hormone status and nutritional state more accurately than total IGF-1 levels alone.