A review of current knowledge about the importance of iodine among women of child-bearing age and healthcare professionals

Iodine is required for thyroid hormone synthesis and fetal neurogenesis. Recent population studies in the United Kingdom (UK) have found iodine deficiency among schoolgirls, women of child-bearing age and pregnant women. This review explores knowledge and awareness of iodine among women of child-bearing age and healthcare professionals (HCPs) in the UK, set within a global context. We aimed to identify gaps in iodine knowledge in the current UK setting of iodine deficiency without iodine fortification and where iodine is not included in antenatal guidelines. The search terms ‘iodine knowledge’ and ‘iodine awareness’ were used to identify relevant papers. Iodine knowledge is poor among women of child-bearing age in the UK according to four studies using questionnaires and qualitative methods. They were unsure of dietary sources of iodine and were not consistently provided with relevant information from HCPs during clinical care. Midwives have been recognised as the main providers of dietary information during pregnancy and, although they recognised the importance of their role in providing nutrition advice, they did not feel equipped to do so and lacked confidence in addressing nutritional concerns. Globally, there was a similar lack of knowledge, however, this was somewhat improved by the inclusion of iodine in antenatal care guidelines. Midwives’ knowledge of iodine was poor, as was knowledge among women of child-bearing age. Improved HCP knowledge and effective communication of information to pregnant women and women planning to conceive may help to improve iodine status which is of particular concern in pregnancy

Thyroglobulin levels among iodine deficient pregnant women living in Northern Ireland

BACKGROUND: Iodine deficiency has re-emerged among pregnant cohorts in the UK. Thyroglobulin (Tg) is a protein produced uniquely by the thyroid gland which appears to mount a U-shaped response to extremes of iodine status. Tg has been suggested as an alternative marker for chronic iodine deficiency but the value of Tg in pregnancy has not been fully elucidated. A recent non-European study suggested a median Tg ≤10 µg/L with 44 µg/L was indicative of sufficiency in the second trimester of pregnancy. METHODS: We measured serum Tg levels in each trimester in 241 pregnant women living in Northern Ireland, a population with mild iodine deficiency at all stages of pregnancy as defined by urinary iodine concentration (UIC) and iodine: creatinine ratio (ICR). Women with Tg antibodies (6% in 1st trimester) were excluded. RESULTS: The median UIC in this cohort was in the deficient range at 73, 94 and 117 µg/L in sequential trimesters (adequacy ≥ 150 µg/L). Corresponding median Tg levels were 19, 16 and 16 µg/L respectively. Median Tg for all samples was 17 μg/L (IQR 11–31) suggestive of iodine deficiency. Tg was >44 μg/L in 14.3%, 9.4% and 12.4% of women in sequential trimesters respectively. Women with either UIC/ICR below the cut-offs 150 µg/L and 150 µg/g creatinine had higher Tg concentrations in 1st and 2nd trimester (p < 0.01; p < 0.001) but not in 3rd trimester. CONCLUSION: This study adds to the evolving evidence that Tg measurement is of value in reflecting iodine status in pregnancy