High TSH Levels TSH levels above 4.0 mUI/mL occur when your thyroid gland is not producing enough thyroid hormone. When there is a low amount of thyroid hormone in the blood—a condition known as ...

A total T4 test detects levels of both bound and free T4, while a free T4 test only identifies free T4 levels. A healthcare provider may also recommend a TSH test to assess thyroid function.

The current reference measures were defined as a thyroid-stimulating hormone level 0.45 mIU/L to 4.5 mIU/L and a total thyroxine level of 57.92 nmol/L to 169.9 nmol/L. Specific reference ranges ...

Medically reviewed by Kelly Wood, MD Normal thyroid-stimulating hormone (TSH) levels generally fall between 0.5 and 5.0 milliunits per liter (mU/L). If your TSH level is higher than 5.0 mU/L it ...

BACKGROUND: Screening in pregnancy for subclinical hypothyroidism, often defined as thyroid-stimulating hormone (TSH) greater than 2.5 mIU/L or greater than 4.0 mIU/L, is controversial. We determined ...

BACKGROUND: Prescribing of levothyroxine and rates of thyroid function testing may be sensitive to minor changes in the upper limit of the reference range for thyroid-stimulating hormone (TSH) that ...

Editor's Note: Contributing Editor Ricki Lewis was diagnosed with thyroid cancer in 1993 and had standard treatment. She will be taking a recently approved test this summer and hopes to participate in ...