Family Health Institute, Breastfeeding Research Center, Tehran University of Medical Sciences, Tehran, Iran.
Nutrition and Endocrine Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, P.O. Box: 19395-4763, Tehran, Iran.
Biol Trace Elem Res. 2018 Sep;185(1):71-77. doi: 10.1007/s12011-018-1246-9. Epub 2018 Jan 25.
There is no scientific consensus on whether breast milk iodine concentration (BMIC) accurately reflects iodine status in lactating mothers and breastfed infants. This study aimed to compare BMIC and maternal urinary iodine concentration (UIC) as indicators of iodine status in breastfed neonates. In this cross-sectional study, 147 lactating mothers and their neonates (3-5 days postpartum) were randomly selected from health care centers. Breast milk and urine samples were collected from each mother and neonate, and a heel-prick blood sample was taken from all neonates as part of a congenital hypothyroidism screening program. According to the World Health Organization criteria, median urinary iodine concentration (UIC) ≥ 100 μg/L in lactating mothers and neonates indicates iodine sufficiency. In areas of iodine sufficiency, median BMIC ≥ 100 μg/L is considered an adequate level. Overall, 129 (89.0%) and 16 (11.0%) mothers had BMICs ≥ 100 and ˂ 100 μg/L, respectively. Median (interquartile range [IQR]) maternal UIC was 70 μg/L (42-144 μg/L) and 37 μg/L (25-100 μg/L) in mothers with breast milk iodine levels ≥ 100 and ˂ 100 μg/L, respectively (P = 0.047); values for UIC of neonates born to mothers with BMICs ≥ 100 and ˂ 100 μg/L were 230 μg/L (114-310 μg/L) and 76 μg/L (41-140 μg/L), respectively (P < 0.001). In the linear regression model, neonate UIC was positively associated with BMIC in both unadjusted (β = 0.558, P < 0.001) and adjusted analysis (β = 0.541, P < 0.001). A similar result was found in logistic regression analysis, indicating that neonates born to mothers with BMIC ≥ 100 μg/L were more likely to have UIC ≥ 100 μg/L compared to those whose mothers had BMIC < 100 μg/L in both unadjusted (OR = 7.93, P < 0.001) and adjusted analysis (OR = 7.29, P = 0.001). The present findings indicate that BMIC is a more sensitive indicator than maternal UIC for assessment of iodine status in breastfed neonates. To address low levels of maternal UIC, further studies on the prescription of supplements containing 150 μg/day iodine during lactation period are warranted.
母乳碘浓度（BMIC）是否能准确反映哺乳期母亲和母乳喂养婴儿的碘状况，目前尚无科学共识。本研究旨在比较 BMIC 和母体尿碘浓度（UIC）作为母乳喂养新生儿碘状况的指标。在这项横断面研究中，从保健中心随机抽取了 147 名哺乳期母亲及其新生儿（产后 3-5 天）。从每位母亲和新生儿采集母乳和尿液样本，并对所有新生儿进行足跟采血，作为先天性甲状腺功能减退症筛查计划的一部分。根据世界卫生组织标准，哺乳期母亲和新生儿的 UIC 中位数（UIC）≥100μg/L 表示碘充足。在碘充足的地区，中位数 BMIC≥100μg/L 被认为是足够的水平。总的来说，129 名（89.0%）母亲的 BMIC≥100μg/L，16 名（11.0%）母亲的 BMIC＜100μg/L。UIC 中位数（四分位距 [IQR]）分别为 70μg/L（42-144μg/L）和 37μg/L（25-100μg/L），母亲的母乳碘水平≥100μg/L 和＜100μg/L（P=0.047）；母亲的 BMIC≥100μg/L 和＜100μg/L 的新生儿 UIC 值分别为 230μg/L（114-310μg/L）和 76μg/L（41-140μg/L）（P＜0.001）。在未调整（β=0.558，P＜0.001）和调整分析（β=0.541，P＜0.001）中，新生儿 UIC 与 BMIC 呈正相关。在逻辑回归分析中也得到了类似的结果，这表明与 BMIC＜100μg/L 的母亲所生的新生儿相比，BMIC≥100μg/L 的母亲所生的新生儿 UIC≥100μg/L 的可能性更高，未经调整（OR=7.93，P＜0.001）和调整分析（OR=7.29，P=0.001）。本研究结果表明，与母体 UIC 相比，BMIC 是评估母乳喂养新生儿碘状况的更敏感指标。为了解决母体 UIC 水平低的问题，需要进一步研究在哺乳期开处方含 150μg/天碘的补充剂。
