Urinary Iodine Status among the Subjects of Autoimmune and Non-Autoimmune Thyroid Disease in Coastal Odisha, India

Background: With universal iodine fortification of table salt, there as been a decrease in the incidence of goitre due to its deficiency. There is an increase in the iodine excretion in urine and this is associated with autoimmune thyroiditis. However the reports are controversial hence this study was designed to see the urine iodine excretion in different groups of thyroid diseases- autoimmune (AITD) and non-autoimmune (NAITD) and compared with euthyroid controls. Methodology: The study included subjects with autoimmune thyroid disorder (AITD) group 1 (n= 95), non-autoimmune thyroid disorder (NAITD) group 2 (n=31) and compared with age and sex matched healthy euthyroid controls group 3 (n=29). Serum free thyroxine (FT4), thyroid peroxidase antibody (TPO Ab), thyroid stimulating hormone (TSH) and median urinary iodine concentration (UIC) in urine were estimated. Results: A statistically significantly higher median UIC was observed in group 1 and 3 as compared to group 2 (p=0.001). According to iodine nutrition status, in group 1, 51 subjects (53.68%) were in moderate iodine deficit state which was statistically significant when compared between group 2, 08(25.80%) p=0.01 and group 3, 10(34.48%) p=0.003. The NAITD group 2 subjects were more iodine deficit than the groups 1 and 3. There was positive correlation between median UIC and TSH (r = 0.36, P = 0.326) and with TPO (r = 116, P=0.075). Conclusion: NAITD subjects are more iodine deficient than the AITD subjects or the euthyroid controls. The UIC was significantly more in AITD than NAITD (p=0.001). We observed a positive correlation between UIC and TPO Ab titres. In adults the incidence of thyroid diseases has increased which may not be directly caused by iodine excess as our study reveals.