Growth hormone binding protein - physiological and analytical aspects.

Area of Science:

• Endocrinology
• Molecular Biology
• Biochemistry

Background:

• Growth hormone (GH) circulates partially bound to GH binding protein (GHBP).
• GHBP generally mirrors the GH receptor's extracellular domain, with species-specific variations in origin and regulation.
• GHBP concentrations correlate with GH status, body composition, and other physiological factors.

Purpose of the Study:

• To explore the role and measurement of GHBP in understanding GH physiology.
• To investigate the relationship between GHBP levels and GH receptor status.
• To assess the clinical utility of GHBP measurement in differentiating endocrine disorders.

Main Methods:

• Review of existing literature on GHBP.
• Description of evolving methodologies for GHBP quantification, from chromatography to immunoassays.
• Clinical case examples illustrating GHBP's diagnostic value.

Main Results:

• GHBP concentrations are linked to GH status and indirectly reflect GH receptor availability.
• Laron's syndrome, a GH receptor defect, is associated with low or undetectable GHBP.
• Modern immunoassays provide direct and reliable GHBP measurements.

Conclusions:

• GHBP serves as a valuable indirect marker of GH receptor status.
• GHBP measurement is clinically useful for differentiating GH deficiency from GH insensitivity.
• Absence of GHBP is a key indicator in diagnosing GH insensitivity.