Automated 22-kD growth hormone-specific assay without interference from Pegvisomant

Area of Science:

• Endocrinology
• Assay Development
• Biochemical Analysis

Background:

• Significant variability exists in growth hormone (GH) assays due to calibration, antibody specificity, and interference.
• GH receptor antagonist Pegvisomant poses a challenge for existing GH assays.
• Consensus recommendations were established for GH assay standardization and evaluation.

Purpose of the Study:

• To develop and evaluate a new GH assay on the automated IDS-iSYS analyzer.
• To address interference issues encountered with Pegvisomant and GH binding protein (GHBP).
• To meet the criteria set forth by a recent consensus conference on GH assay standardization.

Main Methods:

• Developed a new GH assay using monoclonal antibodies, one specific for 22-kD GH and non-reactive to Pegvisomant.
• Assessed isoform specificity and GHBP interference, comparing with existing Siemens Immulite and Diasorin Liaison assays.
• Measured GH concentrations in healthy volunteers and acromegaly patients, and analyzed GH during Pegvisomant treatment.

Main Results:

• The IDS-iSYS GH assay demonstrated high analytical and functional sensitivity (0.01 μg/L and 0.04 μg/L).
• Achieved low intra-assay (2-4%) and inter-assay (5-7%) coefficients of variation.
• The assay showed specificity for 22-kD GH, was unaffected by GHBP, and importantly, was not impacted by Pegvisomant, unlike other assays.

Conclusions:

• The new IDS-iSYS GH assay adheres to recent consensus recommendations for standardization.
• It provides a reliable and accurate tool for measuring growth hormone levels.
• The assay effectively overcomes interference from Pegvisomant and GHBP, improving diagnostic utility.