Assessment of thyroid function during and after treatment of thyrotoxicosis

Outcome of patients with Graves' disease after long-term medical treatment guided by triiodothyronine (T3) suppression test

The value of the T3 suppressed 20-min uptake test for the prediction of post-treatment outcome was studied in 193 unselected patients with Graves' disease treated with thionamide drugs and T3. One hundred and twenty-nine of 193 patients were studied previously and followed thereafter (Group A). Sixty-four were newly treated patients: thirty-three (Group B) were treated at the same hospital as Group A; thirty-one (Group C) were treated at another hospital. In total 126 patients out of 193 satisfied our criteria for suppression (total suppression rate, 65%). The suppression rate for new patients (55% in Group B, 52% in Group C) was similar to that for Group A in 1977 (49%) after comparable duration of treatment. The suppression rate for Group A increased with prolongation of the treatment period (49% in 1977 and 71% in 1981). As to the time course of suppression, it was observed that about two-thirds of the suppressed patients satisfied the criteria for suppression within 3 years of starting treatment. The number of suppressed patients per year decreased thereafter as the treatment periods increased. However, the yearly suppression rate did not decrease with time. The time course of suppression in each patient could not be predicted from the results of initial thyroid function tests. The overall remission rate among the 120 suppressed patients followed for 1-13 (mean, 4) years was 96%, which was almost equal to the value obtained in Group A in 1977 (95%) with the average follow-up period of 2 years. Among the 46 patients in Group A followed for 5-13 (mean, 7) years, no increase in relapse was observed with prolonged follow-up periods. Examination on the relationship between the duration of treatment and the post-treatment outcome revealed that, as a whole, the duration of treatment for the patients with relapse were rather short as compared with those for the patients in remission. These results confirm the usefulness of our T3 suppression test for predicting sustained remission of Graves' disease after treatment, and clearly indicate that long-term medical therapy could increase the number of remissions in patients with Graves' disease.

Goiter: an approach to management

The incidence of goiter (any swelling of the thyroid, either diffuse or localized) varies from five to ten percent in the adult population. Carcinoma of the thyroid is rare, occurring in approximately 2.5 per 100,000 population. The prognosis is generally good. Clinically patients usually present in one of four ways: goiter alone, goiter with pain, hyperthyroidism or hypothyroidism. An approach to the management of this problem is presented, keeping these facts in mind.

Technetium uptake in the management of thyrotoxicosis

The thyroid uptake of 99m-technetium after 7 days of triiodothyronine was measured at the end of a course of antithyroid drugs in ninety-seven patients with thyrotoxicosis who were then followed up for at least 1 year. The relapse rate in sixty-six patients in whom the uptake was suppressed to less than 4% was 21% whereas it was 90% in those patients in whom the uptake was more than 4%. A prediction of the outcome on the basis of whether the uptake was more or less than 4% would have been correct in 82% of patients. Serial tests during treatment show that a correct prediction could have been made one year after starting treatment in 86% of cases depending on whether the uptake at that time suppressed to more or less than 6%. The initial unsuppressed 99m-technetium successfully predicted the likelihood of relapse after a course of antithyroid drugs in 75% of patients. We recommend that alternative therapy should be advised in those patients whose uptakes fail to suppress below 6% after 1 year of drug therapy.