Related Experiment Videos
Growth hormone assays: early to latest test generations compared
M L'Hermite-Balériaux1, G Copinschi, E Van Cauter
1Center for the Study of Biological Rhythms (CERB), School of Medicine, Université Libre de Bruxelles, Belgium. mbaleria@med.ulb.ac.be
Clinical Chemistry
|November 1, 1996
Summary
The immunochemiluminometric assay (ICMA) offers superior detection limits for growth hormone (GH) analysis compared to IRMAs and RIA. This enhanced sensitivity is crucial for accurately assessing GH profiles, especially in obese individuals.
Area of Science:
- Endocrinology
- Clinical Chemistry
- Assay Development
Background:
- Accurate measurement of growth hormone (GH) is essential for diagnosing endocrine disorders and monitoring treatment.
- Existing immunoassays for GH exhibit varying detection limits and performance characteristics, potentially impacting the analysis of 24-hour GH profiles.
- Obesity can influence GH secretion patterns, necessitating sensitive assays for reliable assessment.
Purpose of the Study:
- To compare the analytical performance of four different GH immunoassays: one immunochemiluminometric assay (ICMA), two immunoradiometric assays (IRMAs), and one radioimmunoassay (RIA).
- To evaluate the ability of these assays to detect and quantify GH pulses in 24-hour profiles from normal and obese subjects.
- To assess the concordance between assays, particularly at low GH concentrations relevant to physiological pulsatility.
Main Methods:
- Analysis of 508 serum samples from four normal and four obese subjects using four distinct GH immunoassays.
- Determination of assay detection limits, ranging from 0.02 µg/L (ICMA) to 0.4 µg/L (RIA).
- Statistical comparison of GH concentrations, including correlation coefficients and concordance (r² values) at different concentration thresholds.
Main Results:
- The ICMA demonstrated the lowest detection limit (0.02 µg/L) and detected all GH pulses with peak values > 1 µg/L.
- Overall correlation between assays exceeded 0.90, but concordance varied significantly at low GH levels (< 0.25 µg/L).
- The ICMA showed a lower percentage of undetectable values (0% in normal, 12% in obese) compared to an IRMA (29% in normal, 38% in obese).
Conclusions:
- The ICMA exhibits superior sensitivity and lower undetectable rates for GH measurement compared to IRMAs and RIA, particularly important for analyzing GH profiles in normal and obese individuals.
- Assay selection is critical for accurate GH assessment, especially when evaluating low physiological concentrations and pulsatile secretion.
- The findings highlight the need for sensitive immunoassays to reliably characterize GH dynamics across different physiological states.