The 20-minute iodine uptake in Graves' disease. 3. Prognostic value

The early (20-min.) radioiodine uptake was used to monitor disease activity in 35 Graves' patients undergoing an 18-month course of treatment with carbimazole and T3. T3 alone produced no change in uptake, but four weeks after the introduction of carbimazole, the mean uptake had fallen by more than 50%. Six months after completion of treatment, 20 patients (group R) had relapsed, and 15 (group E) were in remission. The only quantitative difference in mean uptake behaviour between R and E patients was one of degree, their slopes being parallel. Thus, while the mean uptake of both groups fell progressively towards normal, that of group E patients arrived much the earlier, and carbimazole seemed to hasten both. Major fluctuations in thyroid uptake were observed in most individuals, but certain defined patterns emerged. While the uptake suppressed at some time during treatment in 32 (91,4 %) patients, remission was associated only with early (ie before month 5) and stable suppression. The predictive value of the uptake test early during treatment was limited to identifying a group certain to relapse, but these non-suppressors accounted for only 40% of all patients, and it was not possible to identify with any certainty those who would ultimately remit