摘要：a c k g r o u n d: Heavy metals, such as lead (Pb), mercury (Hg), and cadmium (Cd), are known toxicants, but their associations with the thyroid axis have not been well quantified at U.S. back-ground levels.oB j e c t i v e s: We investigated the relationships between thyroid hormones (total and free thyrox-ine [TT4and FT4], total and free triiodothyronine [TT3and FT3], thyroid-stimulating hormone [TSH], and thyroglobulin [Tg]) and levels of Pb, Hg, and Cd in blood and Cd in urine.Me t h o d s: We separately analyzed a sample of 1,109 adolescents (12–19 years of age) and a sample of 4,409 adults from the U.S. National Health and Nutrition Examination Survey (NHANES) 2007–2008. We estimated associations after adjusting for age, sex, race, urinary iodine, body mass index, and serum cotinine.re s u l t s: The geometric mean (GM) levels of blood Pb (BPb), total Hg, and Cd were 0.81 μg/dL, 0.47 μg/L, and 0.21 μg/L in adolescents and 1.43 μg/dL, 0.96 μg/L, and 0.38 μg/L in adults, respec-tively. The GMs of urinary Cd were 0.07 and 0.25 μg/g creatinine in adolescents and adults, respec-tively. No consistent pattern of metal and thyroid hormone associations was observed in adolescents. In adults, blood Hg was inversely related to TT4, TT3, and FT3and urinary Cd was posi tively associated with TT4, TT3, FT3, and Tg, but there were no associations with Pb. Associations were relatively weak at an individual level, with about 1–4% change in thyroid hormones per interquartile range increase in Hg or Cd.co n c l u s i o n s: Our analysis suggests an inverse association between Hg exposure and thyroid hor-mones, and a positive association between Cd exposure and thyroid hormones in adults
关键词：cadmium; heavy metals; lead; mercury; thyroid hormones
