By Mary Shomon
Updated April 11, 2014
Until 2002, the official TSH "normal range" that laboratories and most doctors used throughout the U.S. was a range of 0.5 to 5.0.
On that range, a TSH under 0.5 (a low TSH) indicated hyperthyroidism (an overactive thyroid), and a TSH over 5.0 (a high TSH) indicated hypothyroidism (an underactive thyroid.)
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