POSITIVE CORRELATION OF THE LONG-ACTING THYROID STIMULATOR (LATS) WITH THE PERCENTAGE OF ENDOGENOUSLY LABELLED 131I TRIIODOTHYRONINE IN THE PLASMA OF HYPERTHYROID PATIENTS

Abstract

ABSTRACT The five times concentrated gamma globulins of the plasma of 28 hyperthyroid patients were tested by the McKenzie bioassay. Evidence for the presence of LATS was obtained in 22 patients. In order to compare the numerical values of LATS obtained at different times they were corrected, using a laboratory standard, which was tested in each assay, and the mean regression coefficient of three dose response curves of the laboratory standard. The corrected LATS values were then compared with the percentage of 131I T3 in the patients' plasma 24 hours after a therapeutic dose of 131I. There was no difference in the 1311 T3 between the LATS-negative and the LATS-positive subjects, but in the LATS-positive subjects there was a significant positive correlation between the percentage of 1311 T3 and the LATS values (correlation coefficient 0.793; P < 0.001). No correlation could be found between LATS and the relative concentrations of the other labelled iodo-aminoacids in the plasma.