No abstract

Background:We conducted a study in a metropolitan area to establish regional reference intervals for thyreotropin (TSH) and the thyroid hormones free triiodthyronine (fT3) and free thyroxine (fT4). This was due to the different reference ranges, based on varying regional trials, presented for a widely used electrochemiluminescence immunoassay system. Methods: We investigated 292 apparently healthy adult subjects and excluded those with known history of thyroid disease, abnormal findings in the ultrasonographic examination of the thyroid gland, or elevated thyroid autoantibodies in serum. Accordingly, 204 of 292 subjects were included as the reference collective. We measured serum