Backgruound: The common reference intervals (RIs) for thyroid hormones currently used in China are provided by equipment manufacturers. This study aimed to establish thyroid hormone RIs in the population of Lanzhou, a city in the subplateau region of northwest China, and compare them with previous reports and manufacturer-provided values.
Methods: In total, 3,123 individuals (1,680 men, 1,443 women) from Lanzhou, an iodine-adequate area of China, perceived as healthy were selected. The Abbott Architect analyzer was used to determine the serum concentration of thyroid hormones. The 95% RI was estimated using the 2.5th and 97.5th percentiles as the lower and upper reference limits, respectively.
Results: The serum levels of thyroid-stimulating hormone (TSH), total triiodothyronine (TT3), antithyroglobulin (ATG) antibody, and antithyroid peroxidase (ATPO) antibody levels were significantly correlated with sex (P<0.05). TSH, total thyroxine (TT4), and ATPO levels were significantly correlated with age (P<0.05). The serum levels of TSH, ATG, and ATPO in men were significantly lower than in women; in contrast, the serum TT3 level was significantly higher in men than in women (P<0.05). Serum TSH, TT3, TT4, and ATG levels differed across age groups (P<0.05), but no such variation was observed for ATG levels (P>0.05). The established RIs of TSH, ATG, and ATPO in this study differed between sexes (P<0.05). The thyroid hormone RIs established herein were inconsistent with the manufacturer-provided values.
Conclusion: The RIs of thyroid hormones in the healthy population of Lanzhou were inconsistent with those in the manufacturer's manual. Validated sex-specific values are required for diagnosing thyroid diseases.
Keywords: Anti-thyroglobulin; China; Female; Male; Reference range; Thyroid hormones; Thyrotropin.