Recombinant human thyrotropin stimulation prior to 131I therapy in toxic multinodular goitre with low radioactive iodine uptake

Abstract

Aim: Stimulation with recombinant human thyrotropin (rhTSH) increases thyroid radioiodine uptake, and is an aid to ¹³¹I therapy in non-toxic multinodular goitre (MNG). However, there are not many studies using rhTSH prior to ¹³¹I in toxic multinodular goitre to improve hyperthyroidism and compressive symptoms.

Material and method: A prospective study was conducted on patients with MNG and hyperthyroidism. Patients were recruited consecutively and divided into group I, stimulated with 0.3mg of rhTSH before radioiodine therapy, and a control group or group II, without stimulation. Thyroid function, radioiodine thyroid uptake, thyroid weight, and compressive symptoms were measured, and patients were followed-up for 9 months.

Results: Group I consisted of 16 patients (14 women), with a mean age 69.7 years, and group II with 16 patients (12 women), with a mean age 70.7 years. After stimulation with 0.3mg rhTSH in group I, ¹³¹I uptake (RAIU) at 24h increased by 78.4%, and the estimated absorbed dose by 89.3%. In group II, the estimated absorbed dose was lower than group I after stimulation with rhTSH (29.8Gy vs. 56.4Gy; P=0.001). At 9 months of follow-up, hyperthyroidism was controlled in 87.5% of patients in group I, and 56.2% in group II (P=0.049). The mean reduction in thyroid weight was higher in group I than in group II (39.3% vs. 26.9%; P=0.017), with a tendency towards subjective improvement of compressive symptoms in group I, although non-significant. Only 2 patients described tachycardias after rhTSH administration, which were resolved with beta-blockers.

Conclusion: Stimulation with 0.3mg of recombinant human thyrotropin prior to radioiodine therapy achieves a reduction in thyroid weight and functional improvement in patients with hyperthyroidism and multinodular goitre with low uptake, and with no need for hospital admission.

Keywords: Bocio multinodular; Bocio multinodular tóxico; Hipertiroidismo; Hyperthyroidism; Multinodular goitre; Radioiodine; Radioyodo; Toxic multinodular goitre; rhTSH.