To the Editor.
—I have several questions about the article by Dr Singer and colleagues.1 At the end of the abstract, the authors state that the guidelines are written with the "expectation that more effective care can be provided, and at a cost savings." As the guidelines do not seem to depart in any particularly radical fashion from current practice, I would be interested in hearing the author's explanation for the cost savings.The article suggests that patients who are being treated with levothyroxine for hypothyroidism should have thyroid-stimulating hormone (TSH) concentrations measured annually. My own observations lead me to feel comfortable with a 2-year interval between measuring TSH in otherwise healthy, stable asymptomatic patients (who have been on the same dose of levothyroxine sodium for at least a year with two normal TSH measurements a year apart). Can the authors provide any data to suggest that a 2-year