Growth hormone: isoforms, clinical aspects and assays interference.

Area of Science:

• Endocrinology
• Clinical Chemistry
• Biochemistry

Background:

• Growth hormone (GH) measurement is crucial for diagnosing GH deficiency and excess.
• GH exists as various molecular isoforms, with 22 kDa GH (22K-GH) being the predominant form in circulation.
• The physiological roles and pathological significance of different GH isoforms are not fully understood.

Purpose of the Study:

• To address the discrepancies in GH assay results due to differential recognition of GH isoforms.
• To highlight the importance of standardizing GH immunoassays for accurate clinical diagnosis.
• To advocate for the adoption of 22K-GH specific assays calibrated against a reference preparation.

Main Methods:

• Review of existing studies on GH isoform secretion and biological actions.
• Analysis of the impact of GH isoform heterogeneity on immunoassay performance.
• Examination of efforts towards standardization of GH assays globally.

Main Results:

• While GH isoforms are secreted together, 22K-GH concentrations generally reflect total GH secretion.
• Different GH immunoassays exhibit variable recognition of GH isoforms, leading to result discrepancies.
• Standardization efforts recommend using 22K-GH specific assays calibrated against the 98/574 reference preparation.

Conclusions:

• Standardizing GH assays with 22K-GH specific methods can improve diagnostic accuracy for GH-related conditions.
• Improved assay standardization will facilitate more reliable comparison of GH results across different laboratories.
• Adoption of recommended standardization practices is essential for better patient diagnosis and management.