Which quantitative method in determination of the thyroid hormone levels is more consistent with the clinical symptoms of the thyroid disorders?

Various methods have been used to determine thyroid-stimulating hormone (TSH) and thyroid hormone concentrations in medical diagnostic laboratories. Selection of a suitable method for diagnosis and monitoring thyroid disorders is necessary. The study aimed to compare chemiluminescent assay (CLA), radioimmunoassay (RIA), and enzyme-linked immunosorbent assay (ELISA) methods for the determination of thyroid hormone levels in human serum. Blood samples were taken from 137 patients with thyroid disease and 58 healthy subjects. The sera were analyzed simultaneously to determine the concentration of TSH, thyroxine, and triiodothyronine by CLA, RIA, and ELISA methods. Significant correlation ranges from 0.663 to 0.876 were found between the methods. CLA was the most sensitive method (100 %), but RIA was the most specific method (100 %) according to the clinical symptoms. RIA was the most specific method for the diagnosis of the thyroid diseases, and CLA assay was the most sensitive method in the detection of thyroid diseases except for measuring T4 concentration in hypothyroidism. RIA showed the highest specificity when it comes to the diagnosis of hypothyroidism. RIA had the highest sensitivity, and CLA showed the highest specificity for all three tests in euthyroid group. Each of the methods showed good sensitivity, specificity, and accuracy. ELISA was found to be suitable for the initial screening of the thyroid disorders. The specificity and sensitivity of CLA and RIA were equally high, proposing them as valuable methods for monitoring patients. However, apart from the hazardous effects of ionizing radiation for environment, RIA is the most reliable method for the quantification of thyroid hormones.