Assessment of Iodine Concentration in Human Milk from Donors: Implications for Preterm Infants

Preterm infants are particularly vulnerable to developing iodine deficiency. Donor human milk (DHM) is the preferred feeding option if the mother's own milk (MOM) is not available, but information on DHM iodine concentration (DHMIC) is lacking. Hence, we aimed to assess DHMIC to further evaluate the adequacy of iodine provision in preterm infants. Finally, associations that might influence DHMIC were studied. In 113 donors, we measured iodine intake by evaluating dietary records for five consecutive days with the DIAL (R) Software. From the second day of dietary record, donors provided human milk samples (at least one per day) for four consecutive days. Daily human milk samples were analyzed for DHMIC. A DHMIC >= 200 mu g/L was considered an adequate iodine content for preterm infants. DHMIC and urine iodine concentration (UIC) were determined using ICP-MS. In our study, 83.2% of donors had a full-term infant. Breastfeeding time range was 1.5-49.4 months. During the dietary record, 55.8% took iodine-containing supplements, providing 40-200 mu g/day of iodine. The medians (p25, p75) UIC and DHMIC were 112.4 (75.8, 160.1) and 148.5 (97.6, 206.1) mu g/L, respectively. In this iodine-sufficient population, 70% had a DHMIC of <200 mu g/L. Donors' intake of iodine-containing supplements was associated with higher DHMIC.

Automated summary

Preterm infants are at high risk for iodine deficiency, and donor human milk is the preferred feeding option. However, information on the iodine concentration in donor human milk is lacking. This study aimed to evaluate the iodine concentration in donor human milk and assess its adequacy for preterm infants. The results showed that 70% of donor human milk had iodine concentration below the recommended level in this iodine-sufficient population.