The ultrasensitive TSH is also known as 3rd generation TSH. Each TSH generation shows improved sensitivity on the lower end of the TSH range.
* 1st generation TSH - sensitivity down to 1 or 2 mU/L (could not detect between euthyroid levels and hyperthyroidism)
* 2nd generation TSH - sensitivity down to 0.1 or 0.2 mU/L
* 3rd generation/ultrasensitive TSH - sensitivity down to 0.01 or 0.02 mU/L.
Excerpt from The TSH Reference Range Wars: What's "Normal?", Who is Wrong, Who is Right...
"In their article, they point to some key facts, including:
* In an iodine-sufficient population, the mean TSH is 1.5
* In African-Americans with low incidence of Hashimoto's thyroiditis, the mean TSH is 1.18, which suggests that "this is close to the true normal mean for a normal population"
* When people with positive antithyroid antibodies or family history of autoimmune thyroid disease are excluded from the "reference range" cohort, the normal reference range becomes .4 to 2.5"
AACE recommended many years ago that TSH range be changed to 0.3-3.0. So, yes, yours is borderline.
Do you have symptoms?
Did they test anything else besides TSH?
"Ultra sensitive" is just a description of the accuracy of the test kit.