Xiaochun Teng1, Zhongyan Shan1, Chenyan Li1, Xiaohui Yu1, Jinyuan Mao1, Weiwei Wang1, Xiaochen Xie1, Jianling Du2, Shaowei Zhang3, Zhengnan Gao4, Xiaomei Zhang5, Ling Li6, Chenling Fan1, Weiping Teng1. 1. 1 Department of Endocrinology and Metabolism, Endocrine Institute, and Liaoning Provincial Key Laboratory of Endocrine Diseases, The First Hospital of China Medical University , Shenyang, China . 2. 2 Department of Endocrinology, The First Affiliated Hospital of Dalian Medical University , Dalian, China . 3. 3 Department of Endocrinology, No·202 Hospital of People's Liberation Army , Shenyang, China . 4. 4 Department of Endocrinology, Dalian Municipal Central Hospital Affiliated of Dalian Medical University , Dalian, China . 5. 5 Department of Endocrinology, Peking University , International Hospital, Beijing, China . 6. 6 Department of Endocrinology, Shengjing Hospital of China Medical University , Shenyang, China .
Abstract
BACKGROUND: Pregnant women are highly vulnerable to iron deficiency (ID) due to the increased iron needs during pregnancy. ID decreases circulating thyroid hormone concentrations likely through impairment of iron-dependent thyroid peroxidase. The present study aimed to explore the association between ID and hypothyroxinemia in a retrospective cohort of pregnant women in China. METHODS: To investigate the relationship between ID and hypothyroxinemia, 723 pregnant women were retrospectively analyzed, including 675 and 309 women in the second and third trimesters, respectively. Trimester-specific hypothyroxinemia was defined as free thyroxine (fT4) levels below the 2.5th percentile of the reference range with normal serum thyrotropin (TSH) or TSH higher than the 97.5th percentile of the reference range in each trimester of pregnancy. Serum TSH, fT4, thyroid peroxidase antibodies, thyroglobulin antibodies, serum ferritin, soluble transferrin receptor, and urinary iodine concentrations were measured. Serum ferritin, soluble transferrin receptor, and total body iron were used to indicate the nutritional iron status. RESULTS: Cross-sectional multiple linear regression analysis showed that iron status was positively associated with serum fT4 levels in the first and second trimesters of pregnancy, but not in the third trimester. Logistic regression analysis showed that ID was an independent risk factor for hypothyroxinemia (odds ratio = 14.86 [confidence interval 2.31-95.81], p = 0.005 in the first trimester and odds ratio = 3.36 [confidence interval 1.01-11.21], p = 0.048 in the second trimester). The prospective analysis showed that pregnant women with ID during the first trimester of pregnancy had lower serum fT4 levels and a higher rate of hypothyroxinemia in the second or third trimester than those without ID. CONCLUSIONS: ID appears to be a risk factor to predict hypothyroxinemia in the first and second trimesters of pregnancy, but not in the third trimester. Pregnant women with ID in the first and second trimesters should be regarded as a high-risk group for maternal hypothyroxinemia.
BACKGROUND: Pregnant women are highly vulnerable to iron deficiency (ID) due to the increased iron needs during pregnancy. ID decreases circulating thyroid hormone concentrations likely through impairment of iron-dependent thyroid peroxidase. The present study aimed to explore the association between ID and hypothyroxinemia in a retrospective cohort of pregnant women in China. METHODS: To investigate the relationship between ID and hypothyroxinemia, 723 pregnant women were retrospectively analyzed, including 675 and 309 women in the second and third trimesters, respectively. Trimester-specific hypothyroxinemia was defined as free thyroxine (fT4) levels below the 2.5th percentile of the reference range with normal serum thyrotropin (TSH) or TSH higher than the 97.5th percentile of the reference range in each trimester of pregnancy. Serum TSH, fT4, thyroid peroxidase antibodies, thyroglobulin antibodies, serum ferritin, soluble transferrin receptor, and urinary iodine concentrations were measured. Serum ferritin, soluble transferrin receptor, and total body iron were used to indicate the nutritional iron status. RESULTS: Cross-sectional multiple linear regression analysis showed that iron status was positively associated with serum fT4 levels in the first and second trimesters of pregnancy, but not in the third trimester. Logistic regression analysis showed that ID was an independent risk factor for hypothyroxinemia (odds ratio = 14.86 [confidence interval 2.31-95.81], p = 0.005 in the first trimester and odds ratio = 3.36 [confidence interval 1.01-11.21], p = 0.048 in the second trimester). The prospective analysis showed that pregnant women with ID during the first trimester of pregnancy had lower serum fT4 levels and a higher rate of hypothyroxinemia in the second or third trimester than those without ID. CONCLUSIONS: ID appears to be a risk factor to predict hypothyroxinemia in the first and second trimesters of pregnancy, but not in the third trimester. Pregnant women with ID in the first and second trimesters should be regarded as a high-risk group for maternal hypothyroxinemia.
Entities:
Keywords:
hypothyroxinemia; iron deficiency; pregnant; retrospective study
Authors: Dina K Gaynullina; Svetlana I Sofronova; Ekaterina K Selivanova; Anastasia A Shvetsova; Anna A Borzykh; Olga S Tarasova Journal: Curr Res Physiol Date: 2021-12-14