Factors modifying growth hormone estimates in immunoassays

Area of Science:

• Endocrinology
• Clinical Chemistry
• Biochemical Assays

Background:

• Human serum growth hormone (GH) measurement has been a diagnostic tool for over 30 years.
• Early radioimmunoassays using polyclonal antibodies showed low specificity and variable results.
• Modern assays use monoclonal antibodies, offering improved specificity but highlighting the need to understand assay influences.

Purpose of the Study:

• To emphasize the importance of understanding factors influencing growth hormone (GH) assays.
• To address the need for sophisticated diagnostic methods, particularly for adult GH deficiency.
• To highlight the relevance of accurate GH estimation in the context of GH substitution therapy for adults.

Main Methods:

• Review of historical and current methods for human serum growth hormone (GH) determination.
• Comparison of radioimmunoassay (RIA) with polyclonal antibodies versus assays using monoclonal antibodies.
• Discussion of factors impacting GH assay variability and interpretation.

Main Results:

• Early GH assays (polyclonal antibodies) yielded higher, less specific results compared to modern monoclonal antibody assays.
• Assay variability necessitated the development of empiric GH cutoff levels in different laboratories.
• Understanding assay influences is critical due to the increasing sophistication of diagnosis and treatment.

Conclusions:

• Accurate measurement of GH is essential for diagnosing growth disturbances and GH disorders.
• Knowledge of factors influencing GH assays is increasingly important for sophisticated diagnostics, especially in adult GH deficiency.
• The relevance of precise GH level estimation is heightened by GH substitution therapy in adults, given the lack of specific symptoms.