Comparison of the measurement of serum TSH concentration by a supersensitive immunoradiometric assay and conventional radioimmunoassay in various types of hyperthyroidism and hypothyroidism
Rajatanavin, R.; Chailurkit, L.; Chalayondeja, W.; Jittivanich, U.
Journal of the Medical Association of Thailand 71(4): 203-208
1988
ISSN/ISBN: 0125-2208 PMID: 3418251 Document Number: 307251
To compare the efficacy of the newly developed supersensitive immunoradiometric assay (IRMA) for serum TSH and the conventional radioimmunoassay (RIA) in differentiating patients with thyroid dysfuntion, we measured serum TSH (IRMA) and TSH (RIA) concentrations concomittantly in various groups of patients. In 26 euthyroid subjects, TSH (IRMA) values ranged from 0.3-4.1 .mu.U/ml (mean .+-. SD = 1.88 .+-. 1.66 .mu.U/ml) while in 39 hyperthyroid subjects TSH (IRMA) values ranged from nondectectable -0.8 .mu.U/ml (mean .+-. 2SD = 0.06 .+-. 0.32 .mu.U/ml). The serum TSH (IRMA) concentrations of 0.3-0.8 .mu.U/ml were overlapping values between some euthyroid and some hyperthyroid patients from postpartum thyroiditis. The measurement of serum TSH (IRMA) concentration gave 84.6 per cent sensitivity in depicting euthyroid subjects while concentration TSH (RIA) did not give any discrimination due to large overlapping of TSH (RI) values between euthyroid and hyperthyroid patients. The measurement of both TSH (IRMA) and TSH (RIA) values gave comparable sensitivity in depicting 21 hypothyroid patients. In borderline hyperthyroidism, the measurement of serum TSH (IRMA) concentration could obviate the need for TRH stimulation test.