Recombinant human TSH increases the efficacy of a fixed activity of radioiodine for treatment of multinodular goitre.

CONTEXT

High doses of (131)I are usually needed in the treatment of multinodular goitre (MNG) for effective thyroid volume (TV) reduction. Recombinant human thyroid-stimulating hormone (rhTSH) is an adjuvant to enhance (131)I uptake, allowing a decrease in radiation activity and enhancing (131)I efficacy.

OBJECTIVE

To evaluate whether rhTSH increases the efficacy of a fixed activity of (131)I for the treatment of MNG.

DESIGN

Two-year, observational, placebo-controlled study.

SETTING

Patients received 0.1 mg rhTSH (A), 0.005 mg rhTSH (B) or placebo (C). A fixed activity of 1.11 GBq of (131)I was administered 24 h after rhTSH or placebo.

PATIENTS

A total of 28 outpatients (26 females and two males) with MNG.

MEASUREMENTS

TSH, free T4, T3, thyroglobulin (Tg) and TV.

RESULTS

Basal radioactive iodine uptake and TV values were comparable among all groups. After rhTSH or placebo, peak levels of TSH, free T4, T3 and Tg were higher in A than in B or in C (p < 0.05). Hyperthyroidism was observed in A (n = 2), B (n = 6) and C (n = 4). Thyroid enlargement was reported in A (n = 3) and B (n = 6). After 24 months, 10 patients developed hypothyroidism (four in A, three in B and three in C). TV reduction was similar between A and B (37.2 +/- 25.5% vs. 39.3 +/- 27.9%, p = 0.88), but different from the non-significant reduction in C (15.3 +/- 28.3%, p = 0.08).

CONCLUSIONS

Followed by 1.11 GBq, a very low dose of 0.005 mg rhTSH was equally safe and effective as 0.1 mg rhTSH. Both doses increased the efficacy of radioiodine. Adverse events were mild, transient and readily treatable.