The optimal index for iodine deficiency in pregnancy andthe evaluation of iodine-related nutritional habits

Objective: This study aimed to evaluate the urinary iodine levels, thyroid function tests, their relationship with nutrition and the optimal marker for evaluating the iodine status of pregnant women in a total of 227 pregnant women in six Afyonkarahisar central family health centers. Materials and Methods: This analytical and cross-sectional study was conducted with 227 pregnant women aged 18-49 who applied for routine control and follow-up between 01 March and 01 September 2022. Sociodemographic information was obtained from the pregnant women by face-to-face survey method. Blood and urine samples were taken to study iodine, creatinine and thyroid function tests. SPSS 20 package program was used in the data analysis, and p<0.05 was considered significant. Results: The median age of the participants was 27.0 (4.9) years. 87.2% of the participants used iodized salt. The median value of urine iodine concentration (UIC) of the pregnant women was 59.0 μg/L and 90.8% of them were iodine deficient. The median value of 24-hour urine iodine excretion (24h-UIE) was 111.2 μg/day. There was no significant difference in the UIC and the 24h-UIE value between trimesters. The median value of the urine iodine/creatinine ratio (UIC/UCr) was 72.7 μg/g. Although 24h-UIE value was positively correlated with UIC/UCr and UIC, the correlation coefficient was higher with UIC/UCr. In addition, when the predictive power of UIC and UIC/UCr values to determine the adequacy of iodine intake was tested with the ROC curve, it was seen that the UIC/UCr value was superior to the UIC value. These data support that the UIC/UCr value is superior to the UIC value in determining the recent iodine intake of pregnant women. The median thyroid stimulating hormone (TSH) value of the pregnant women was 2.05 mIU/L, and the median fT4 value was 1.07 ng/dL. When the thyroid function test results were evaluated was found to be 16.3% (n=37) of the participants as subclinical hypothyroidism. There was no significant difference between the iodine status of pregnant women with and without subclinical hypothyroidism. Conclusion: According to the data we obtained from the participatants in our study, the problem of iodine deficiency in pregnant women in Afyonkarahisar continues despite using iodized salt. Subclinical hypothyroidism, which has serious obstetric consequences in pregnant women, is very prevalent in our study. UIC/UCr value seems to be stronger than UIC value in showing iodine status in pregnant women. Keywords: Iodine Deficiency in Pregnant Women, Subclinical Hypothyroidism, Family Health Center, Iodine Creatinine Ratio