It depends on the laboratory running the test and any medical conditions you have.
Speaking roughly, normal levels of thyroid-stimulating hormone (TSH) are in the range of 0.4 to 4.0 mIU/L. However, each laboratory and test manufacturer identifies its own normal TSH range. This is based on the test, the equipment being used, and the patients being tested.
The American Association of Clinical Endocrinologists has proposed a range of 0.3 to 3.0 for normal TSH levels. Using these cutoff values would lead to more people being diagnosed with an underactive thyroid (hypothyroidism).
Other experts recommend using 3.0 as the high end of normal for people being treated for a thyroid condition.
If your TSH results fall near the high or low end of normal, the best way to understand them is to talk with your doctor.
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