Evaluation of the relationship between iodine levels and attention deficit hyperactivity disorder symptoms in women of reproductive age

Objective: Iodine is an essential element required for the synthesis of thyroid hormones. Thyroid hormones play a vital role in the development of the central nervous system and the maintenance of neurocognitive functions. Particularly in women, adequate iodine intake during the reproductive period is critical both for their own health and for fetal brain development in potential pregnancies. The aim of this study was to determine urinary iodine levels in nulliparous women of reproductive age living in Konya and to evaluate the relationship between these biochemical indicators and symptoms of attention deficit hyperactivity disorder (ADHD) as well as possible ADHD status. Materials and Methods: This study was approved by the Ethics Committee of Selçuk University Faculty of Medicine with decision number 2025/103 at the meeting held on 25 February 2025. The study was conducted between May 20 and September 26, 2025, at Selçuk University Faculty of Medicine Hospital. The study population consisted of 100 nulliparous women of reproductive age who attended the Family Medicine outpatient clinic of Selçuk University. In accordance with the aim of the study, a questionnaire form was administered to evaluate the sociodemographic characteristics and iodine awareness of the participants, and the Adult ADHD Self-Report Scale (ASRS-v1.1) was used to assess symptoms of attention deficit hyperactivity disorder (ADHD) and possible ADHD status. Venous blood samples were collected from the participants in the morning after overnight fasting for the measurement of thyroid function tests and thyroid antibodies. Urine samples obtained for iodine analysis were stored at −80 °C until analysis. Serum TSH, free T4 (sT4), free T3 (sT3), thyroglobulin (Tg), anti-thyroid peroxidase (anti-TPO), and anti-thyroglobulin (anti-Tg) levels were measured using the electrochemiluminescence immunoassay (ECLIA) method. Urinary iodine concentration was determined by inductively coupled plasma mass spectrometry (ICP-MS) The data were analyzed using the Statistical Package for the Social Sciences (SPSS) version 25.0. A p-value <0.05 was considered statistically significant. Results: The mean age of the women of reproductive age included in the study was 23.45 ± 4.59 years (18–45). The median urinary iodine concentration was 81.80 µg/L, and iodine deficiency (<100 µg/L) was detected in 61.0% of the women. According to the ASRS-v1.1 scale, the prevalence of possible ADHD among women of reproductive age was 33.0%. It was determined that 57.0% of the women used iodized salt. Among women with sufficient urinary iodine levels, the frequency of the response "I have heard about iodine deficiency" was significantly lower compared to those with insufficient iodine levels (p=0.021). Similarly, in comparisons according to awareness level, the median urinary iodine concentrations were significantly lower among women who responded "I have heard about iodine deficiency" (p=0.019) and "I have heard about iodized salt" (p=0.037). No significant association was found between urinary iodine levels and ASRS-v1.1 scores among women of reproductive age. However, TSH levels were significantly higher in women with sufficient or excessive iodine levels compared to those with iodine deficiency (p=0.002). In addition, a statistically significant positive correlation was observed between urinary iodine levels and TSH levels (p=0.002). A statistically significant positive correlation was also found between total ASRS-v1.1 scores and free T3 levels (p=0.040). Conclusion: This study demonstrated that iodine deficiency remains common among women of reproductive age and that there is a discrepancy between knowledge and behavior regarding the use of iodized salt. Increasing short educational interventions in family health centers on the correct selection, storage, and use of iodized salt is important. Considering the increased iodine requirement in women planning pregnancy, iodine levels should be assessed and the daily supplementation of 150 µg iodine recommended by the WHO and international guidelines should be considered within national health policies. In addition, evaluation of thyroid function tests before and during pregnancy is of critical importance for both maternal and fetal health. Since studies investigating iodine status among women of reproductive age are limited in our country, more comprehensive research is needed. Keywords: Attention deficit; Hyperactivity; Iodine level; Women of reproductive age