The study titled Thyroxine and Triiodothyronine Content in Commercially Available Thyroid Health Supplements analyzed 10 over-the-counter thyroid supplements and found that 9 contained detectable levels of triiodothyronine (T3) ranging from 1.3 to 25.4 μg per tablet, while 5 contained thyroxine (T4) in amounts ranging from 5.77 to 22.9 μg per
