Urinary Iodine Levels in Subjects With Thyroid Nodules Compared to Controls

Introduction: The prevalence of thyroid nodule is less than 5% on palpation and is around 65% on ultrasound. The Government of India started universal iodination of salt in 1984 to reduce Iodine deficiency disorders .Previous studies showed that high iodine intake was associated with increased thyroid nodules but some studies showed "U" shaped association between Iodine intake and thyroid nodules. Urinary Iodine concentration has been recommended as it reflects recent iodine intake because it is well accepted, cost-effective, and easily obtainable indicator for iodine status. The data on Iodination and its association with thyroid nodules in India is limited. This study was done to see any association between Iodination and thyroid nodules. Objectives: To compare urinary Iodine levels in patients with thyroid nodules irrespective of thyroid functional status versus age and gender-matched euthyroid controls with no thyroid nodule. Materials and Methods: Study type -Single cross-sectional study. Individuals with age >18 yrs with thyroid nodules were included in the study irrespective of thyroid functional status.Those with history of RadioIodine ablation, intake of Iodine contrast agents,drugs containg Iodine were excluded from the study. Urinary iodine was analyzed by Colorimetric Sandell-kolthoff method at Public health institute, Bengaluru. Results: Out of 223 subjects ,120 were cases[females 97.5%] and 103 were controls [females97.1%]. Mean age in cases and controls was 39.78±11.22yrs, 38.40±11.47yrs respectively; P=0.46. Mean urinary iodine in cases was 16.63±4.35ug/dl versus controls 15.57±4.27ug/dl; P=0.069. Anti Tpo and Anti Tg levels were higher in cases compared to controls. Urban and rural population were similar in both groups;p=0.085. The salt was added while cooking by majority[83.3% of controls and 87.5% of cases]. Most of the people were consuming Iodised salt compared to Non Iodised salt in both controls [92.2%] and cases[93.3%]. Conclusion: In our study Urinary Iodine conecentration between cases and controls was not different and urinary Iodine concentration did not suggest overiodinationin our population.The development of thyroid nodules can be attributed to varied other reasons like Endocrine disruptors and environmental factors in our subjects.