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The antitumor drug sunitinib can cause hypothyroidism
The background of the study. Sunitinib is a drug that has proven effective in 
patients with some gastrointestinal and kidney tumors. After two patients with gastrointestinal tumors being treated with sunitinib were found to have hypothyroidism, thyroid function was assessed prospectively in a group of patients being treated with sunitinib.
How the study was done. The study subjects were 42 patients with gastrointestinal stromal tumors who had normal serum thyrotropin (TSH) concentrations at base line. The patients were treated with sunitinib in cycles in which they were given the drug daily for two or four weeks followed by two weeks of no therapy. The median duration of sunitinib therapy in these patients was 37 weeks. Patients with high serum TSH concentrations were further evaluated, and some were treated with thyroxine (T4).
The results of the study. During treatment, 15 of the 42 patients (36 percent) had hypothyroidism, as defined by persistently high serum TSH concentrations. Their average base-line serum TSH concentration was 2.1 mU/L (range, 0.7 to 4.6 mU/L) and the maximum concentration was 63.9 mU/L (range, 7.2 to 288). The average time to a persistently high serum TSH concentration was 50 weeks (range, 12 to 94). The risk of hypothyroidism increased with the duration of therapy.
Six of the patients with hypothyroidism (40 percent) had low serum TSH concentrations (hyperthyroidism) before having high concentrations. Thyroid ultrasonography in two patients with hypothyroidism revealed small thyroid glands.
Among the 27 patients who did not have persistent hypothyroidism, 4 (15 percent) had low serum TSH concentrations, but stopped the drug and were not studied again, and 7 (26 percent) had one or more slightly high serum TSH values but later had normal values.
The conclusions of the study. The antitumor drug sunitinib can cause hypothyroidism.
The original article. Desai J, Yassa L, Marqusee E, George S, Frates MC, Chen MH, Morgan JA, Dychter SS, Larsen PR, Demetri GD, Alexander EK. Hypothyroidism after sunitinib treatment for patients with gastrointestinal stromal tumors. Ann Intern Med 2006;145:660-4.
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| Thyroid Digest Index | | | March 2007 Thyroid Digest |
