Our Experience with the Suppression Test in the Diagnosis of Thyroid Dysfunctions (415 Tests)

Abstract

SummaryWithin a total of 3 600 I131 thyroid uptake measurements performed, 415 thyroid suppression tests were carried out, using the method of Werner and Spooner.Administration of tri-iodothyronine resulted in an average depression of the I131 uptake by 80% in euthyroid patients without goitre and with nontoxic diffuse goitre, and by 65% in patients with non-toxic nodular goitre. There was on the average no depression in patients with toxic goitres.In toxic patients treated with I131, the suppression test has proved to be of value as a means to control the effectiveness of the therapy. Those patients who, after treatment, showed no further clinical symptoms of hyperthyroidism responded with an appreciable reduction of the thyroid uptake, whereas in those patients who still remained toxic after therapy the uptake did not change. The reduction was less significant in those patients who, although clinically cured, were still exophthalmic.A comparison between the results of thyroid uptake, PBI131 and suppression tests done in the same patient indicated that the results of the suppression tests are more in accordance with the clinical picture than those of the PBI131.The suppression test is of considerable value in the differential diagnosis between normal cases and patients suspected of hyperfunction not only before but also after radioiodine therapy.