MSCPNT / Department of Nutrition / Introduction: Iodine is an essential nutrient required by humans for the synthesis of thyroid hormones, which are vital for normal growth and development. Objective: The primary aim of the study was to describe the iodine status of lactating mothers and infants aged from 0 to 6 months in the Vhembe and Mopani Districts. Methods: A cross-sectional study conducted on 246 infant-mother pair, from the Mopani and the Vhembe Districts. Data was gathered using a questionnaire. Breastmilk, mother urine, infant urine, household salt and drinking water were collected to be analysed for iodine content. Results: The median of breastmilk iodine concentration level amongst lactating mothers in the Vhembe District was 101.4 µg/l (IQR 62.9 – 175.1 µg/l) and 154.4 µg/l (IQR 92.6 – 211.8 µg/L) in Mopani. The median UIC of mothers in Vhembe was 98.5 (IQR 57.66 – 153.93), whereas in the Mopani District the median UIC of mothers was 126.08 µg/l (IQR 69.89 – 206.71 µg/L). The median UIC of infants in Vhembe was 220 (IQR 106.67 – 418.43 µg/l) and in the Mopani District was 321.94 µg/l (IQR 167.96 – 482.66 µg/l). Conclusion: The BMIC in the study signifies iodine sufficiency in both the Vhembe and the Mopani Districts. The results of this study suggest that the BMIC be included in studies assessing iodine status in lactating mothers since the UIC only reflects iodine that was consumed recently. The UIC may under estimate the maternal iodine status if it is not complemented by the BMIC data. / NRF

Hypothyroidism is a common endocrine disorder affecting women of reproductive age. On a global level, iodine deficiency is still the most common cause of hypothyroidism. Also genetic variations, in particular SNP rs4704397 in the PDE8B gene, are responsible for a significant proportion of TSH variations.  Untreated hypothyroidism has significant adverse effects on pregnancy and fetal outcome. Most international guidelines suggest targeted thyroid testing in pregnant women with risk factors for thyroid disturbances. In a case-control study, an association between homozygous A/A as well as homozygous G/G carriers of SNP rs 4704397 in PDE8B and recurrent miscarriage was found. The explanation for this association is unknown. In a nationwide survey, all guidelines for thyroid testing and management of hypothyroidism during pregnancy in Sweden were collected and compared with international guidelines. The local guidelines were variable and poorly compliant with the international guidelines. In a follow-up in one district, 5,254 pregnant women were included for subsequent review of their medical reports. We found a targeted thyroid testing rate of 20.1% in clinical practice, with an overall frequency of women with trimester-specific elevated TSH of 18.5%. More disturbingly, half of the women who were on levothyroxine treatment at the time of conception had an elevated TSH level at thyroid testing. In a subsequent cohort study of the 5,254 women, we found the prevalence of trimester-specific elevated TSH and overt hypothyroidism to be equal in targeted thyroid tested and untested women. In a cross-sectional study, a median urinary iodine concentration (UIC) of 98 μg/l was found in the study population. According to WHO/UNICEF/IGN criteria, the population-based median UIC during pregnancy should be 150-249 μg/l. In conclusion, genetic variations may contribute to adverse pregnancy outcomes. In clinical practice, thyroid testing and the management of hypothyroidism during pregnancy is unsatisfactory, regarding the whole chain from development of local guidelines to their implementation and to targeted thyroid testing. Moreover, our results indicate insufficient iodine status in the pregnant population of Sweden.