[Thyroxine vs iodine and thyroxine. Comparison of the TSH suppression test]

In a crossover study 20 subjects (12 with non-toxic goiter) were given 150 micrograms levo-thyroxine (LT4) or a combination of 100 micrograms LT4 and 100 micrograms iodide daily for 8 weeks. Group I took 150 micrograms LT4 and group II the combination. After 4 weeks the two groups switched medications. A clinical examination, an intravenous TRH test and thyroid sonography were performed before the start of the study and 4 and 8 weeks thereafter. 150 micrograms LT4 daily resulted in significantly higher TSH suppression than the combination. A decrease in thyroid volume from 45 ml (mean range 24-85) to 26 ml (17-70 ml) was registered after as little as 4 weeks' therapy in 12 of 20 subjects with goiter.