High Urinary Iodine Concentration Among Breastfed Infants and the Factors Associated with Iodine Content in Breast Milk
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Iodine deficiency in infants leads to delayed growth and development. Some studies have reported iodine deficiency among infants and lactating women. We assessed iodine status in infants and lactating women, as well as the iodine content in breast milk. A cross-sectional study enrolled mother-infant pairs (infants aged 4–6 months), who visited Well Child Clinic at Ramathibodi Hospital, Bangkok, Thailand. Infants were classified by feeding type as breastfed (BF), mixed breastfed and formula-fed (MF), and formula-fed (FF). Demographic and perinatal data were collected. The urinary iodine concentration (UIC) of infants and lactating women, and breast milk iodine concentration (BMIC) were analyzed. Seventy-one infants were enrolled. The median UIC of infants was 282 mcg/L. Breastfed infants had higher median UIC than formula-fed infants (553 vs. 192 mcg/L; p = 0.002). Forty-eight percent of infants had a UIC more than 300 mcg/L. The median UIC and BMIC of lactating women were 149 and 255 mcg/L, respectively. Among the BF group, the infant UIC was correlated with maternal UIC (rs = 0.857, p = 0.014). Multiple linear regression showed the BMIC to be associated with maternal UIC (β = 4.03, 95% CI [1.34, 6.71]) and maternal weight (β = 8.26, 95%CI [2.76, 13.77]). Iodine nutrition among our study population was adequate. The median UIC of infants and lactating mothers were 282 and 149 mcg/L, respectively. Breastfed infants had a significantly higher median UIC than formula-fed infants. The BMIC was associated with maternal UIC and maternal weight.
KeywordsIodine status Breastfed infants Urinary iodine concentration Breast milk iodine concentration Breastfeeding
We express our sincere thanks to all participants in our study, healthcare personnel at the well child clinic and lactation clinic of the Faculty of Medicine of Ramathibodi Hospital for their cooperation. We are grateful to Professor Pat Mahachoklertwattana for his suggestions on the manuscript, and Miss UmapornUdomsubpayakul for her assistance in statistical analyses. We thank Arshad Makhdum, PhD, from Edanz Group (www.edanzediting.com/ac) for editing a draft of this manuscript.
This study was funded by the Development Potential of Thai People Project, Faculty of Medicine, Ramathibodi Hospital, Mahidol University.
Compliance with Ethical Standards
The study protocol was approved by the Committee of Human Rights Related to Research Involving Human Subjects, Faculty of Medicine of Ramathibodi Hospital, Mahidol University, Bangkok, Thailand (protocol number 01-54-01). All mothers provided written inform consent before enrollment. All procedures performed in the study were in accordance with the ethical standards of the committee and with the 1964 Helsinki declaration.
Conflict of Interest
The authors declare that they have no conflict of interest.
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