An assessment of urinary and breast milk iodine concentrations in lactating mothers from Gorgan, Iran, 2003

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 mu g/L were considered consistent with iodine deficiency. Forty-three percent of women had grade 1 and 2 goiters, respectively. The median UIC was 259 mu g/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 mu g/L. The median MIC was 93.5 mu g/L. MIC was less than 50 mu g/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.