Preliminary data on radioiodine treatment of multinodular goiters in elderly patients preceded by stimulation with human recombinant TSH

In most elderly patients with multinodular goiter, surgical treatment of a large, compressive goiter with mediastinal invasion, may be contraindicated because of increased risks of co-morbidities. Radioactive iodine therapy has been alternatively used in these patients. The majority of RAI treated patients have a 50% reduction of goiter size within 12-24 months. Common complications are late-onset hypothyroidism and the possibility of autoimmune thyroid disease (Graves' disease). Serum TSH is commonly suppressed in these patients due to slightly elevated serum free T4 (due to increased iodine ingestion). In order to increase the goiter uptake of RAI we have used 0.45 mg IM of recombinant human TSH (rhTSH) preceding the therapeutic doses of RAI. Ten patients (60-81 ys-old)were treated with RAI (60-170 mCi). The size of the goiter was evaluated by CT scan and echography (60.8-283.5g). Five of these patients with suppressed serum TSH levels received rhTSH, increasing serum TSH levels to 35-58 mU/L at 24hs, when the RAI doses was administrated. The extent of the efficacy of ablation therapy was indirectly evaluated by serial assays of serum Tg concentrations (IRMA) and by quantitative reverse transcription - PCR measurement of Tg mRNA in the peripheral blood (Ringel et al., JCEand M 84:4037, 1999). Before RAI treatment, serum Tg levels ranged from 81.2-802.9 ng/mL, increasing to 906.8-1,972.0 ng/mL in the first week post-therapy. Similarly after RAI, there was a marked elevation of quantitative Tg mRNA expressed as pg Tg mRNA Eq/mcg thyroid mRNA. There was no statistical difference between the group of patients pre-treated with rhTSH (n=5) and those without exogenous TSH stimulation (n=5). In 6 patients anti-TPO antibodies became positive after RAI therapy. Two patients had a positive TRAb test without clinical or laboratory evidence for Grave's disease. Thyroid volume was reduced to 50-60% of the pre-treatment size in the first year of RAI therapy. Four patients had radiation esophagitis that was alleviated by anti-inflammatory agents. We conclude that RAI therapy of large MN goiters is a safe and effective treatment for elderly patients. Serum Tg and serum Tg mRNA may indicate the extent of tissue radiation destruction and rhTSH may be useful to increase the efficacy of the ablation therapy