Micronutrient Research Office, Endocrine Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
Iran's Ministry of Health and Medical Education, Tehran, Iran.
J Endocrinol Invest. 2021 Oct;44(10):2307-2314. doi: 10.1007/s40618-021-01538-z. Epub 2021 Mar 11.
Although Iran has been considered iodine replete since 2000, the first national survey of iodine intake among Iranian pregnant women in 2014 indicated that despite the adequate intake of iodine by the general population, this vulnerable group has moderate iodine deficiency. Therefore, in this national cross-sectional interventional study, we aimed to assess the iodine intake and thyroid function of Iranian pregnant women 2 years after implementing national iodine supplementation for this vulnerable group.
In this cross-sectional study, we conducted a national interventional survey of pregnant women. A total of 1200 pregnant women (400 women from each trimester) from 12 provinces of Iran were recruited from the antenatal care clinics from October 2018 to March 2019. The median urinary iodine concentration (MUIC), as an indicator of iodine status in three spot urine samples, was measured, along with the serum total T4 (TT4), thyrotropin (TSH), thyroglobulin (Tg), thyroid peroxidase antibody (TPO-Ab), and iodine content of household salt.
The mean age of the cohort was 28 ± 6.2 years, with the mean gestational age of 22.7 ± 13.0 weeks. The overall MUIC (IQR) of pregnant women was 188 µg/L (124.2-263 µg/L). Also, the MUICs in the three trimesters of pregnancy were 174 µg/L (110-254), 175 µg/L (116-251), and 165 µg/L (114-235), respectively. The MUICs ≥ 150, 100-149, and < 100 µg/L were found in 63, 19.8, and 16.2% of the subjects, respectively. The mean TT4 level was 12 ± 4.5 µg/dL, and the median (IQR) level of TSH was 2.37 mIU/L (1.66-3.18 mIU/L). According to our local reference range, 118 (10.5%) pregnant women had subclinical hypothyroidism, 6 (0.53%) women had isolated hypothyroxinemia, and 65 (5.7%) women were TPO-Ab positive. Also, the median (IQR) level of Tg was 10.08 µg/dL (5.7-20.4 µg/dL), and the median iodine content of household salt was 29.6 µg/g; the iodine content was ≥ 30 µg/g in 85% of household salt. The results showed that more than 95% of households were under iodized salt coverage.
The results of this study indicated that iodine supplementation with at least 150 µg of iodine per day improved the iodine intake of pregnant women. Except for subclinical hypothyroidism, the prevalence of clinical hypothyroidism, clinical/subclinical thyrotoxicosis, TPO-Ab positivity, and isolated hypothyroxinemia decreased significantly, which emphasizes the importance of iodine supplementation during pregnancy.
尽管伊朗自 2000 年以来被认为碘充足，但 2014 年对伊朗孕妇进行的首次全国碘摄入量调查表明，尽管一般人群碘摄入量充足，但这一脆弱群体仍存在中度碘缺乏。因此，在这项全国性的横断面干预性研究中，我们旨在评估在为这一脆弱群体实施全国性碘补充 2 年后伊朗孕妇的碘摄入量和甲状腺功能。
在这项横断面研究中，我们对孕妇进行了全国性的干预性调查。2018 年 10 月至 2019 年 3 月，从伊朗 12 个省份的产前保健诊所招募了 1200 名孕妇（每个孕期 400 名）。我们测量了 3 份随机尿液样本的中位数尿碘浓度（MUIC），以评估碘状况，同时还测量了血清总 T4（TT4）、促甲状腺激素（TSH）、甲状腺球蛋白（Tg）、甲状腺过氧化物酶抗体（TPO-Ab）和家用盐中的碘含量。
队列的平均年龄为 28±6.2 岁，平均妊娠龄为 22.7±13.0 周。孕妇的总体 MUIC（IQR）为 188µg/L（124.2-263µg/L）。此外，妊娠三个时期的 MUIC 分别为 174µg/L（110-254）、175µg/L（116-251）和 165µg/L（114-235）。MUIC≥150、100-149 和<100µg/L 的分别占 63%、19.8%和 16.2%。平均 TT4 水平为 12±4.5µg/dL，中位数（IQR）TSH 水平为 2.37 mIU/L（1.66-3.18 mIU/L）。根据我们当地的参考范围，118（10.5%）名孕妇患有亚临床甲状腺功能减退症，6（0.53%）名孕妇患有孤立性甲状腺素血症，65（5.7%）名孕妇 TPO-Ab 阳性。此外，Tg 的中位数（IQR）水平为 10.08µg/dL（5.7-20.4µg/dL），家用盐的中位数碘含量为 29.6µg/g；85%的家用盐中的碘含量≥30µg/g。结果表明，超过 95%的家庭使用的是加碘盐。
这项研究的结果表明，每天至少补充 150µg 碘可改善孕妇的碘摄入量。除亚临床甲状腺功能减退症外，临床甲状腺功能减退症、临床/亚临床甲状腺功能亢进症、TPO-Ab 阳性和孤立性甲状腺素血症的患病率显著下降，这强调了妊娠期间补充碘的重要性。
