Short-term results of Na131I treatment of hyperthyroidism evaluated using an extended dosimetric method.

Abstract

To assess and evaluate the short-term results of radio-iodine treatment using an extended dosimetric method. Sixty-five patients with Graves disease (GD) and 32 patients with toxic multinodular goitre (TMG) received a pre-therapeutic dosage of Na123I. The overall indicative radiation dose (Dind) and the indicative dosage (Aind) was calculated for the individual patient using the dosimetric results found. In the therapeutic setting dosimetric measurements were performed again. The quotient of the administered dose (A) and the indicative dosage and the quotient of the absorbed radiation dose (Dabs) and the indicative radiation dose were used to evaluate treatment results after 1 year of follow-up. Clinical outcome after 1 year for GD was 26% hyper-, 48% eu- and 26% hypothyroidism and for TMG 32, 59 and 9%, respectively. Within the percentile range P25-P75 of A/Aind these results were 27, 46 and 27% for GD and 36, 64 and 0% for TMG. Within the percentile range P25-P75 of Dabs/Dind these results were 23, 59 and 18% for GD and 33, 67 and 0 for TMG. Correlation coefficients between pre- and therapeutic dosimetric measurements in GD and TMG were 0.76 and 0.38, respectively. The short-term outcome after 1 year of follow-up is 48 and 59% euthyroidism for GD and TMG, respectively. Clinical outcome within the percentile range P25-P75 of A/Aind did not change these results. Within the percentile range P25-P75 of Dabs/Dind euthyroidism was achieved in 59% and 67% for GD and TMG, respectively. The pre-therapeutic values inaccurately represent the therapeutic values for GD and even more for TMG.