Changes in the IGF-IGFBP axis in critical illness.

Area of Science:

• Endocrinology
• Critical Care Medicine
• Metabolic Regulation

Background:

• Serum concentrations of growth hormone-dependent insulin-like growth factors (IGFs) decrease in critical illness.
• This decrease is linked to transient growth hormone resistance and altered growth hormone secretion patterns.
• Nutritional deficiency and inflammatory cytokines also contribute to reduced IGF levels.

Purpose of the Study:

• To investigate the alterations in IGFs and their binding proteins (IGFBPs) in critical illness.
• To explore the role of growth hormone secretion patterns and inflammatory factors in these changes.
• To assess the potential prognostic value of IGFBP-1 in critically ill patients.

Main Methods:

• Analysis of serum concentrations of IGF-I, IGF-II, and various IGFBPs (IGFBP-1, IGFBP-2, IGFBP-4, IGFBP-5, IGFBP-6) in critically ill patients.
• Correlation of IGF and IGFBP levels with growth hormone secretion patterns, nutritional status, and inflammatory markers.
• Evaluation of IGFBP-1 levels as a predictor of patient outcomes.

Main Results:

• Growth hormone-dependent IGF complexes are decreased, associated with less pulsatile growth hormone secretion.
• Growth hormone-independent IGFBPs (IGFBP-2, IGFBP-4, IGFBP-6) increase, indicating IGF redistribution.
• IGFBP-1 levels are elevated on intensive care unit admission, potentially decreasing with nutritional support, and may predict outcomes.

Conclusions:

• Critical illness profoundly affects the IGF system, involving altered growth hormone dynamics and IGFBP profiles.
• IGF redistribution occurs, shifting from ternary to binary complexes with specific IGFBPs.
• IGFBP-1 emerges as a potential prognostic biomarker in critically ill patients.