Endocrine Abstracts

Background: A re-emergence of mild iodine deficiency in the United Kingdom (UK) has been reported. A recent UK study suggested a dose dependent relationship between mild maternal deficiency and a number of childhood cognitive scores. The World Health Organisation defines sufficiency in a population as a median urinary iodine concentration (UIC) 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/day during pregnancy. Thyroglobulin (Tg) has been suggested as an alternative indicator of iodine status. No cut off value is available in adults but a study in children defined sufficiency as a median Tg value ≤13 μg/l and/or <3% of samples ≥40 μg/l.

Methods: Participants (n=241) were recruited at their booking visit and followed up at each trimester and into the postpartum period. Dietary intake was collected with four day food diaries and iodine specific food frequency questionnaires. Urinary samples were obtained from 80 offspring for UIC. A separate cohort (n=183) was recruited to evaluate nutrition knowledge during pregnancy.

Results: The maternal median UIC was 72 μg/l, 94 μg/l and 116 μg/l for 1st, 2nd and 3rd trimesters respectively. In the post-natal period, median UIC was 90 μg/l in women and 148 μg/l in infants. Mean iodine intake was 133 μg/day in the first trimester. First trimester median serum Tg was 19 μg/l with 18% of samples >40 μg/l. Only 30%, 15% and 9% were aware that seafood, eggs or dairy were good sources of iodine respectively. Only 5% felt they had sufficient knowledge about iodine compared to 90% when asked about folate.

Conclusion: Our study suggests that pregnant women living in NI are iodine deficient but offspring have adequate status. Currently there is no food iodine fortification program in the UK. Pregnant women are not advised how to optimise intake and public health initiatives are required.