Iodine isotope (131I) therapy for toxic nodular goitre: treatment efficacy parameters

Abstract

BACKGROUND: When planning radioactive iodine therapy, itfrequently happens, both in Poland and world-wide, that inadequateattention is paid to such easily measurable parametersas: 1) the serum concentration of thyrotropin (TSH) beforeadministering radioiodine, which is a key factor for extranodular(non-autonomous) iodine uptake of the thyroid gland, 2) thyroidgland iodine uptake, and 3) the effective half-life of 131I (Teff.). Theaim of the study is to evaluate the impact of the above factorson the efficacy of 131I treatment in hyperthyroid patients.

METHODS: The material consisted of 4140 patients: 2190 withautonomous toxic nodules (ATN) and 1950 with toxic multinodulargoitres (TMG). The patients were prepared for treatment insuch a way that the concentration of TSH did not exceed 0.1 mU/land Teff.< 5 days. The therapeutic activity of 131I was calculatedusing Marinelli’s formula. The selection of absorbed dose valuewas determined by the degree of suppression of extranodulartissue. Monitoring was performed every eight weeks.

RESULTS: At one year after 131I administration showed thata euthyroid status was achieved in 94%, hypothyroidism was seen observed in 3%, while persistence or recurrence of hyperthyroidismin 3% of ATN patients and, respectively, 89%, 4% and7% of TMG patients.

CONCLUSIONS: Patients with toxic nodular goitre who are to betreated with radioiodine should have the lowest possible serumconcentration of TSH. The suppression of extranodular determinesthe optimal value of absorbed dose for Marinelli’s formula.