by Amber Cox, originally published on the Healio website on November 9, 2016
Iodine deficiency in pregnant women from Northern Ireland is common, but offspring have adequate iodine levels, according to a recent study.
“A re-emergence of mild iodine deficiency in the United Kingdom has been reported,” the researchers wrote. “A recent U.K. study suggested a dose-dependent relationship between mild maternal deficiency and a number of childhood cognitive scores. [WHO] defines sufficiency in a population as a median urinary iodine concentration of 100 µg/L in non-pregnant women and infants and 150 µg/L during pregnancy. It also recommends a daily intake of 250 µg/L during pregnancy.”
Paul McMullan, of the Regional Centre for Endocrinology and Diabetes at Royal Victoria Hospital in Ireland, and colleagues evaluated data from 241 pregnant women from Northern Ireland monitored for iodine levels in the urine. Four-day food diaries and iodine-specific food frequency were used to record dietary intake. Urinary iodine concentrations in 80 offspring were also recorded.
Maternal median urinary iodine concentration was 72 µg/L, 94 µg/L and 116 µg/L in the first, second and third trimesters, respectively. During the postnatal period, women had a median urinary iodine concentration of 90 µg/L, and infants had a median urinary iodine concentration of 148 µg/L. In the first trimester, the median iodine intake was 133 µg/L.
“Thyroglobulin has been suggested as an alternative indicator of iodine status,” the researchers wrote. “No cutoff value is available in adults, but a study in children defined sufficiency as a median [thyroglobulin] value 13 µg/L and/or < 3% of samples 40 µg/L.”
During the first trimester, the median serum thyroglobulin value was 19 µg/L, and 18% of samples had concentrations at least 40 µg/L.
Nutrition knowledge during pregnancy was evaluated in a separate cohort of 183 women. Compared with 90% of these participants who reported they had sufficient knowledge of folate, 5% reported sufficient knowledge of iodine. Seafood was reported as a good source of iodine by 30%, eggs by 15% and dairy by 9%.
“Our study suggests that pregnant women living in Northern Ireland are iodine deficient and have not been provided with the knowledge to improve this,” McMullan said in a press release. “Pregnant women are warned about the dangers of folic acid deficiency and fetal development, but few appear to be aware of the effect of iodine deficiency. Ninety percent of the women we interviewed felt informed about folic acid whilst only 5% had knowledge regarding iodine.
“Although levels in the infants of this study were adequate, probably due to concentrating ability of iodine in breast milk and adequate levels in formula feed, the impact of low levels at the start of pregnancy, when brain and nerve health is most critical, is uncertain and therefore of concern.”
McMullan P, et al. Abstract #OC6.4. Presented at: Society for Endocrinology Annual Conference; Nov. 7-9, 2016; Brighton, United Kingdom.