Yeqing Gu1, Vu Thi Quynh Chi1, Qing Zhang2, Li Liu2, Ge Meng1,3, Hongmei Wu1, Xue Bao1, Shunming Zhang1, Shaomei Sun2, Xing Wang2, Ming Zhou2, Qiyu Jia2, Kun Song2, Kaijun Niu1,2,4,5. 1. Nutritional Epidemiology Institute and School of Public Health, Tianjin Medical University, Tianjin, China. 2. Health Management Center, Tianjin Medical University General Hospital, Tianjin, China. 3. Department of Toxicology and Sanitary Chemistry, School of Public Health, Tianjin Medical University, Tianjin, China. 4. Tianjin Key Laboratory of Environment, Nutrition and Public Health, Tianjin, China. 5. Center for International Collaborative Research on Environment, Nutrition and Public Health, Tianjin, China.
Abstract
CONTEXT: Thyroid hormones (THs) have direct and indirect effects on hematopoiesis. However, few studies have directly evaluated the effect of THs on incident anemia among euthyroid subjects. This cohort study aimed to explore whether THs under physiological conditions can affect the development of anemia in the general population. DESIGN: A total of 12,310 participants were enrolled in the cohort study (∼5-year follow-up period; mean, 3.1 years). A chemiluminescence immunoassay was used to measure free T3 (FT3), free T4 (FT4), and TSH, and anemia was defined according to the World Health Organization recommendation. THs, TSH, and Hb were assessed yearly during follow-up. Multivariable Cox proportional hazards regression models were used to assess the association between THs, TSH, and incident anemia. RESULTS: The fully adjusted hazards ratios (95% CI) of anemia per 1-unit change in FT3, FT4, and TSH concentrations were 0.70 (0.56, 0.87), 0.93 (0.88, 0.98), and 1.19 (0.94, 1.50) (P < 0.01, P < 0.01, and P = 0.14, respectively). Moreover, a significant and positive association between FT3, FT4, and annual changes in Hb (standard regression coefficients of 0.056 and 0.028, respectively; both P < 0.01) was observed. Similar associations were observed when the participants who had thyroid dysfunction upon follow-up were excluded. CONCLUSIONS: The current study demonstrated that THs significantly predict future anemia and annual changes in Hb, even in the euthyroid population.
CONTEXT: Thyroid hormones (THs) have direct and indirect effects on hematopoiesis. However, few studies have directly evaluated the effect of THs on incident anemia among euthyroid subjects. This cohort study aimed to explore whether THs under physiological conditions can affect the development of anemia in the general population. DESIGN: A total of 12,310 participants were enrolled in the cohort study (∼5-year follow-up period; mean, 3.1 years). A chemiluminescence immunoassay was used to measure free T3 (FT3), free T4 (FT4), and TSH, and anemia was defined according to the World Health Organization recommendation. THs, TSH, and Hb were assessed yearly during follow-up. Multivariable Cox proportional hazards regression models were used to assess the association between THs, TSH, and incident anemia. RESULTS: The fully adjusted hazards ratios (95% CI) of anemia per 1-unit change in FT3, FT4, and TSH concentrations were 0.70 (0.56, 0.87), 0.93 (0.88, 0.98), and 1.19 (0.94, 1.50) (P < 0.01, P < 0.01, and P = 0.14, respectively). Moreover, a significant and positive association between FT3, FT4, and annual changes in Hb (standard regression coefficients of 0.056 and 0.028, respectively; both P < 0.01) was observed. Similar associations were observed when the participants who had thyroid dysfunction upon follow-up were excluded. CONCLUSIONS: The current study demonstrated that THs significantly predict future anemia and annual changes in Hb, even in the euthyroid population.