Endocrine Abstracts

Thiazolidinediones have demonstrated some efficacy in promoting radioiodine uptake of previously poorly radioiodine-responsive thyroid cancers. We describe the effect of rosiglitazone, in promoting uptake in thyroid metastatic tissue with weak uptake in order to treatment with radioiodine in two patients.

Case 1: A 62-year-old woman with thyroid cancer and negative I-131 body scan post therapy (150 mCi) with presence of recurrent disease (PET positive in neck, pulmonary and mediastinum and persistently elevated serum thyroglobulin concentrations). The patient received 8 mg rosiglitazone daily for 3 months. Serum thyroglobulin stimulated before initiation of therapy with rosiglitazone was 37.5 ng/ml. After differentiation treatment, she received 150 mCi I-131 and the posttherapy scan showed marked uptake in the neck and Tg elevation after rTSH to 172.4 ng/ml in contrast to the predifferentiation treatment scan.

Case 2: A 63-year-old woman with thyroid cancer and negative I-131 body scan post therapy (150 mCi) with presence of recurrent disease (PET positive in neck and mediastinum and serum antibody antithyroglobulin elvated 395.8 UI/ml). The patient received 8 mg rosiglitazone daily for 3 months. After differentiation treatment, she received 150 mCi I-131 and the posttherapy scan showed marked uptake in the neck and Ac-antTg elevation to 436.1 UI/ml.

Both patients tolerated treatment well without symptoms of hypoglycemia or change in liver function tests.

Conclusion: Our two patients showed uptake augmentation of I-131 after pretreatment differentiation with rosiglitazone. It might encourage the use of TZDs in patients with radiotherapy resistant differentiated thyroid cancers.