HealthDay News — Levothyroxine treatment is frequently initiated for mildly increased thyrotropin levels, with no change in the median thyrotropin level upon treatment initiation from 2008 to 2018, according to a research letter published online June 21 in JAMA Internal Medicine.

Juan P. Brito, MD, from the Mayo Clinic in Rochester, Minnesota, and colleagues examined the use of levothyroxine in the United States over time using national data for commercially insured and Medicare Advantage enrollees.

A total of 110,842 patients newly initiated levothyroxine treatment between 2008 and 2018; there was no significant change in the median thyrotropin level at treatment initiation, from 5.8 mIU/L to 5.3 mIU/L in 2008 and 2018, respectively (P =.79). The researchers found that in a subset of 58,706 patients with thyrotropin and FT4 or T4 levels available, levothyroxine was initiated for overt hypothyroidism, subclinical hypothyroidism, and normal thyroid levels in 8.4, 61.0, and 30.5%, respectively. From 2008 to 2018, there was an increase in the proportion of adults with overt hypothyroidism, from 7.6 to 8.4% (P =.02), while no change was seen in the proportions with subclinical hypothyroidism (59.3 to 65.7%; P =.36) or normal thyroid function (32.9 to 26.2%; P =.84). Among patients with subclinical hypothyroidism, there was no change noted in the proportion with mild and moderate subclinical hypothyroidism, while the proportion with severe subclinical hypothyroidism decreased.

“These results suggest substantial overuse of levothyroxine during the entire duration of the study, suggesting opportunities to improve care,” the authors write.

One author disclosed financial ties to Johnson & Johnson.

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