Thyroid autoimmunity and thyroid hormone reference intervals in apparently healthy Chinese adults.

Background: Thyroid disorders are common, often go unrecognized, and when left untreated, can have serious public health implications. Dietary and ethnic differences are known to influence thyroid function. However, comparatively few studies have examined the prevalence of autoimmune thyroid disease (AITD) and thyroid function test (TFT) reference intervals in non-Western populations.
Methods: Sera were collected from 486 apparently healthy Chinese adults. Participants were classified as healthy based on physician review of metabolic testing and patient history. TFT (TSH, Free T4, Total T4, Free T3, Total T3, and T-Uptake), thyroid peroxidase autoantibodies (TPO-Ab), and thyroglobulin autoantibodies (Tg-Ab) were measured for all participants.
Results: TPO-Ab and Tg-Ab were found in 12.1% and 10.3% of participants, with higher prevalence found in women. Reference intervals were calculated for all TFT. Gender associated differences in mean values were noted for Total T4, Free T3, Total T3, and T-Uptake, but not for TSH and Free T4.
Conclusions: Laboratory evidence of AITD is common in otherwise healthy Chinese adults. Women are significantly more likely to be positive for TPO-Ab and Tg-Ab, which is of particular concern for women of reproductive age. Reference values specific for the Chinese population were established for thyroid function tests in individuals without AITD.