[Determination of antibody antireceptor of TSH, experience in patients with thyroid disorders and controls]

In order to measure TSH receptor antibodies (TRAb) we tried to set up a radioreceptor assay using human thyroid membranes. Due to lack of appropriate binding activity of the material obtained, we decided to use a kit which provides solubilized porcine membrane-receptors to TSH instead of human membranes, as well as calibrators that have been standardized in a receptor assay against MRC LATS std B. With these reactives we have measured TRAb in sera from 7 normal controls (C), 54 thyrotoxic patients (43 diffuse goiters [BDH], 8 multinodular goiters [BHM] and 3 Subacute Thyroiditis [TSA]), 3 patients with Hashimoto's Thyroiditis (TH) and in 6 non-hyperthyroid Graves ophthalmopathy patients. Measurement were initially performed using calibrators and the results expressed as U/L; since a very good correlation between the expression U/L and the calculated Inhibition Index (I.I.) was found (r = 0.99, n = 15, p < 0.001), results are shown using latter. In C mean +/- SD value for I.I. was 3.4 +/- 2.37%, so we decided to use, as cut off criteria for differentiating between normal and abnormal results, the figure 11%, which represents the mean +/- 3 SD. According to this, 93% of BDH had elevated TRAb activity while only slightly more than one third of MBH had elevated values, this difference being highly significant (p < 0.0001); both TSA and TH patients showed low TRAb activity while all Graves ophthalmopathy pts had elevated values, thus suggesting that they had a latent disease. We concluded that the methodology that is adequate and practical for clinical purposes.(ABSTRACT TRUNCATED AT 250 WORDS)