Effects of long term iodized table salt consumption on serum T3, T4 and TSH in an iodine deficient area of Bangladesh.

The effect of iodized and non-iodized table salt in goiter hyper-endemic area on the thyroid gland and its hormones T3, T4 and Thyroid Stimulating Hormone (TSH) were studied in two hundred subjects from the Center for Nuclear Medicine and Ultrasound, Mymensingh. Iodized and non-iodized salt users were called study and control groups respectively. The mean concentration of T3 were 2.38 nmol/L and 2.22 nmol/L & T4 concentration were 128.67 and 123.72 nmol/L in the study and control group respectively. The mean TSH concentration was 1.52 mIU/L and 1.62 mIU/L in study and control group. The data indicated that continuous and long term use of iodized salt increased both T3, T4 and decreased TSH in such a limit which was not statistically deferent at P< 0.05 level as compared to the control group. There was no significant change in occurrence of (hypo and hyper thyroidism or iodinated salt induced thyrotoxicosis) adverse effect, following iodine supplementation. The study shows that, mandatory mass iodination of table salt consumption in a hyper-endemic iodine deficient area is safe and does not cause any side effect. We suggest close regular monitoring of T3, T4, and TSH and further evaluation by specifically designed studies for any probable link between iodine induced hypo or hyperthyroidism and mass iodination of table salt consumption.