What is the Origin of Tissue Sensitivity Index?

This index concept originates from the study of insulin resistance, which was expanded to encompass resistance patterns across the entire spectrum of endocrine signaling. It reflects the need to move beyond single-organ assessments to evaluate the whole-body impact of hormonal status. The integration of multiple functional endpoints yields a more accurate picture of metabolic efficiency.

What is the Mechanism of Tissue Sensitivity Index?

The mechanism is assessed by examining surrogate markers for tissue response, such as the ratio of free to bound hormones or the expression levels of specific intracellular signaling proteins downstream of the receptor. For example, high adiponectin levels may correlate with improved adipose tissue sensitivity to insulin action. Modulating factors like chronic inflammation or optimizing nutrient cofactors directly supports the molecular machinery required for high tissue sensitivity.

Tissue Sensitivity Index ∞ Area

Tissue Sensitivity Index

Meaning

The Tissue Sensitivity Index is a composite metric quantifying the integrated responsiveness of key peripheral tissues—such as muscle, fat, liver, and brain—to circulating endocrine signals like insulin, cortisol, and sex steroids. A high index indicates that tissues are efficiently translating hormonal presence into appropriate functional output, such as glucose uptake or protein synthesis. Low sensitivity, often termed resistance, signifies a breakdown in the downstream signaling cascade despite adequate hormone levels. This index provides a critical measure of systemic metabolic health.