Impact of Dietary Habit, Iodine Supplementation and Smoking Habit on Urinary Iodine Concentration During Pregnancy in a Catalonia Population

The effect of sodium restriction on iodine prophylaxis: a review

PURPOSE

Sodium is essential to life. However, its dietary excess is detrimental to the cardiovascular system, and sodium restriction is a crucial step in cardiovascular prevention. Iodine deficiency has been fought worldwide for decades, and substantial success has been achieved introducing the use of iodine-enriched salt. Nevertheless, areas of iodine deficiency persist around the world, both in developing and industrialized countries, and a major concern affecting dietary sodium reduction programs is represented by a possible iodine intake deficiency. There are substantial differences in the source of alimentary iodine among countries, such as iodized salt added, household tap water, seafood, or salt employed in packaged food. It is clear that a sodium-restricted diet can induce differences in terms of iodine intake, depending on the country considered. Moreover, iodine status has undergone relevant changes in many countries in the last years.

METHODS

Systematic review of literature evidence about the possible effects of sodium restriction on population iodine status.

RESULTS

To date, the available results are conflicting, depending on country, salt iodization policy, as well as time frame of data collection. However, to ensure an optimal iodine supply by salt fortification, without exceeding the current recommendation by World Health Organization for salt intake, seems to be an achievable goal.

CONCLUSION

A balanced approach may be obtained by an adequate iodine concentration in fortified salt and by promoting the availability of iodized salt for household consumption and food industry use. In this scenario, updated prospective studies are strongly needed.

Assessment of Iodofolic Supplementation on Thyroid Function in Pregnant Women with Iodine Sufficient Status and their Infants in Birjand

BACKGROUND

Maintaining iodine at sufficient levels is necessary throughout the pregnancy to prevent adverse outcomes in infants. This study aimed to assess iodofolic supplementation's impact on thyroid function in women at the end of the third trimesters of gestation.

METHODS

This case-control study was conducted on 130 pregnant women in the Birjand, east of Iran, during the period from August 2017 to February 2019. We assessed iodofolic supplementation effect in the women at the first trimesters of gestation and followed them at the end of the third trimesters and also their infants on days 3-5. Serum samples were obtained from women and infants for measuring levels of thyroid-stimulating hormone (TSH). Urinary iodine concentration (UIC) was also determined at the end of the third trimester.

RESULTS

The median serum TSH concentration in the folic acid consumed group (3.26 ± 1.91) did not significantly differ from another group (2.98 ± 1.41), (p = 0.68). There is also no considerable difference in the mean serum TSH concentration between infants born from mothers who consumed folic acid in the first trimester of pregnancy and another group (p = 0.50). The TSH concentration in all infants was below 5 μM/L. The significant difference in the mean of UIC was also not observed between pregnant women in the folic acid consumed group (188.02 ± 105.38) and iodofolic consumed group (225.77 ± 130.26), (p = 0.13).

CONCLUSION

Iodine intake in our study was sufficient according to the WHO recommendation and idofolic supplementation was not emphasized.

HPLC Analysis of the Urinary Iodine Concentration in Pregnant Women

Iodine is an essential component for fetal neurodevelopment and maternal thyroid function. Urine iodine is the most widely used indicator of iodine status. In this study, a novel validated ion-pair HPLC-UV method was developed to measure iodine concentration in clinical samples. A sodium thiosulfate solution was added to the urine sample to convert the total free iodine to iodide. Chromatographic separation was achieved in a Pursuit XRs C8 column. The mobile phase consisted of acetonitrile and a water phase containing 18-crown-6-ether, octylamine and sodium dihydrogen phosphate. Validation parameters, such as accuracy, precision, limits of detection and quantification, linearity and stability, were determined. Urinary samples from pregnant women were used to complete the validation and confirm the method's applicability. In the studied population of 93 pregnant women, the median UIC was lower in the group without iodine supplementation (117 µg/L, confidence interval (%CI): 95; 138) than in the supplement group (133 µg/L, %CI: 109; 157). In conclusion, the newly established ion-pair HPLC-UV method was adequately precise, accurate and fulfilled validation the criteria for analyzing compounds in biological fluids. The method is less complicated and expensive than other frequently used assays and permits the identification of the iodine-deficient subjects.