Antithyroid drugs are often used before, during, and after radioiodine therapy for hyperthyroidism. But the practice, which has been debated, may significantly raise the risk of treatment failure, say researchers from Switzerland, Denmark, Scotland, and Johns Hopkins University.
The researchers analyzed data from controlled trials involving 1,306 patients. Giving the drugs in the week before treatment sometimes increased failure rates, whereas giving the drug afterward reduced rates of hypothyroidism. There was also a trend toward a higher risk of treatment failure in trials that used fixed radioiodine doses, compared with those that adapted dose calculation according to uptake when antithyroid drugs were given before radioiodine.
The antithyroid drugs may also affect the morbidity and mortality in the year after treatment. Failures of radioiodine treatment include persistent and recurrent hyperthyroidism, the researchers note, which increases cardiovascular risk and necessitates further treatment. Conversely, patients with hypothyroidism require regular and lifelong follow-up for titration of the optimal dose of levothyroxine canadian (Synthroid generic, Abbott).