Serum TSH measurements by a sensitive enzyme immunoassay discriminate euthyroid from hyperthyroid subjects and avoid the need for @entity1218 test during suppressive therapy with XXXX .

@entity1 @entity3935 @entity1955 @entity1218 @entity5651 @entity8531 @entity1374
Serum TSH was determined photometrically by a recently developed enzyme immunoassay (EIA) based on the use of a monoclonal antihuman @entity8531 antibody and a polyclonal antiTSH antibody coupled to horseradish peroxidase. The results obtained in @entity1 with various @entity1374 and in normal controls were compared with those achieved by conventional double antibody radioimmunoassay (RIA). In normal subjects, serum TSH was detectable in all cases by EIA (values ranging from 0.27 to 5.1 mU/L), but only in 76% by RIA. Ninety-two percent of hyperthyroids had undetectable serum TSH by EIA and the remaining 8% had values between 0.2 and 0.4 mU/L. In clinically euthyroid @entity1 with @entity5651 , 9% had undetectable serum TSH by EIA, suggesting the presence of autonomously functioning areas within the thyroid. Serum TSH under basal conditions and after @entity1218 stimulation was measured in 45 @entity1 on @entity1955 suppressive therapy. Undetectable basal serum TSH by EIA was associated with a lack of TSH response to @entity1218 in 95% of cases. Conversely, 37.5% of @entity1 with undetectable basal serum TSH by RIA had a normal or blunted response to @entity1218 . Detectable basal values were predictive of a normal response to @entity1218 by both methods. These data indicate that basal serum TSH measurement by EIA allows an almost complete differentiation of normal from @entity3935 @entity1 and can avoid the need of the @entity1218 stimulation test.
