Performance characteristics of six third-generation assays for thyroid-stimulating hormone

Area of Science:

• Clinical Chemistry
• Endocrinology
• Assay Development

Background:

• Thyroid-stimulating hormone (TSH) assays are crucial for diagnosing hypothyroidism and hyperthyroidism.
• Current guidelines mandate a functional sensitivity of ≤0.02 mIU/L for TSH assays.
• Assay validation involves analyzing serum samples across multiple reagent lots over several weeks.

Purpose of the Study:

• To evaluate the functional sensitivity of six automated TSH assay methods.
• To compare the performance of these TSH assays across different serum pools and concentrations.

Main Methods:

• Functional sensitivity was determined for Access 2, ADVIA Centaur, ARCHITECT i2000, E170, IMMULITE 2000, and Vitros ECi methods.
• Seven serum pools and two reagent lots per method were utilized for the analysis.
• Method-comparison studies were conducted using samples with TSH concentrations >0.2 mIU/L.

Main Results:

• Functional sensitivities varied, with ARCHITECT i2000 (<0.005 mIU/L) and Vitros ECi (0.004 mIU/L) showing the highest sensitivity.
• Significant differences in mean results were observed between methods, particularly for low TSH concentration pools.
• The ARCHITECT i2000 method demonstrated the highest precision at low TSH levels.

Conclusions:

• Current automated TSH assays exhibit significant variability, impacting comparability of results, especially at concentrations below 0.2 mIU/L.
• Discrepancies exist across the analytic measurement range, necessitating further investigation.
• Harmonization of TSH assay methods is essential for reliable clinical interpretation and patient diagnosis.