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Objective To measure breast milk iodine (MI) and urinary iodine (UI) concentrations in healthy newborns and their nursing mothers from an iodine-sufficient region to determine adequacy and to relate these parameters to thyroid function tests in mothers and infants. Design Cross-sectional. Patients Forty-eight healthy neonates of 37 to 42 weeks’ gestation with normal cord blood TSH values and their mothers were recruited in Tehran, Iran. Measurements Serum thyroid function tests were performed, and maternal and infant urinary iodine excretion, and maternal MI concentration were measured. Results Neonatal age was 12·9 ± 3·9 (mean ± SD; range 7–30) days and maternal age was 25·8 ± 5 years. Median (range) UI in neonates was 271 µg/l (57–800) and in mothers was 107 µg/l (20–710). Median (range) MI was 148 µg/l (45–750). Neonatal and maternal UI did not correlate with serum thyroid function tests. UI < 150, 150–230, and > 230 µg/l was found in 20, 12·5, and 67·5% of neonates and 79·1, 14, and 7% of mothers, respectively. MI was < 150, 150–180, and > 180 µg/l in 52·4, 11·9, and 35·7% of mothers, respectively. Conclusions Among euthyroid neonates, UI was adequate despite low median maternal UI and MI concentrations. There were no significant correlations between UI or MI and thyroid function tests in the mothers and infants. [ABSTRACT FROM AUTHOR]

Objective: To the assess the iodine status of preterm infants born in an area of iodine sufficiency using the urinary iodine concentration (UIC) and thyroid-stimulating hormone (TSH) levels and compare these values across different feeding practices during the first 7 days of life., Methods: In this cross-sectional study, 88 preterm infants born at 30 to 34 weeks of gestation and admitted to the neonatal intensive care unit of a referral hospital in Tehran (Iran) were included. The infant UIC and TSH levels and breast milk iodine concentration in mothers who were exclusively breastfeeding were measured., Results: Median (interquartile range [IQR]) UIC and TSH levels in the study population were 81 (39-189) μg/L and 1.60 (0.80-2.85) mIU/L, respectively. When preterm infants were stratified by the type of feeding, the median (IQR) UICs were 64 (42-126) μg/L in parenteral nutrition, 125 (41-195) μg/L in exclusively breastfeeding, 57 (28-123) μg/L in formula feeding, and 45 (35-132) μg/L in mixed feeding, with no statistically significant difference between the groups (P = .31). The median (IQR) breast milk iodine concentration was 271 (177-521) μg/L in preterm infants exclusively fed their mothers' own milk. There was no significant difference in the proportion of the TSH levels of >5 mIU/L between preterm infants who received enteral and parenteral nutrition (P = .27)., Conclusion: Preterm infants are at risk of iodine deficiency even in an area where the general population has adequate iodine. Only the preterm infants who received exclusively their mothers' own milk had marginally adequate iodine status. Further studies are warranted to determine the necessity of iodine supplementation for this vulnerable group., (Copyright © 2022 AACE. Published by Elsevier Inc. All rights reserved.)

Dietary iodine is essential for the production of thyroid hormones. Breast-fed infants are reliant on maternal iodine intake. The aim of this study was to evaluate iodine sufficiency in lactating women in Iran. The sample consisted of 100 lactating mothers referred to the Taleghani Hospital of Gorgan, Iran. Goiter was graded according to World Health Organization (WHO) classification. Spot urine and breast-milk samples were collected for the measurement of iodine concentrations. Urine iodine concentrations (UIC) less than 100 and breast-milk iodine concentrations (MIC) less than 50 microg/L were considered consistent with iodine deficiency. Forty-three percent of women had grade 1 and 2 goiters, respectively. The median UIC was 259 microg/L. UIC was less than 100 in 16%. Grade 1 and 2 goiters were each present in 8% of mothers with UIC less than 100 microg/L. The median MIC was 93.5 microg /L. MIC was less than 50 microg /L in 19%. Grade 1 and 2 goiters were present in 11% and 8%, respectively, of women with MIC <50 mg/L. MIC and UIC levels were significantly correlated (r = 0.44, p < 0.0001). Iodine deficiency and goiter were associated (p < 0.0001). UIC and MIC concentrations are sufficient in Gorgan, Iran. However, individual infants remain at risk for low iodine intake via breast milk.