Changes of Iodine Nutritional Status in the Elderly after Replacing Iodized Salt with Non-Iodized Salt for Half a Year

China has issued the “Reform Plan of the Salt Industry System” in 2016 and it is necessary to attach the importance to the changes of iodine nutritional status of those people who might consume non-iodized salt for a long time. Forty-six elderly subjects were recruited and replaced iodized salt with non-iodized salt for 6 months. Urine iodine concentration (UIC), dietary iodine intake, thyroid function, thyroid B-ultrasound, and plasma iodine were monitored during the follow-up period. The median dietary iodine intakes of the baseline, the 1st, 2nd,3rd, 4th, and 6th month were 255.3 µg/d, 183.6 µg/d, 164.6 µg/d, 179.2 µg/d, 139.4 µg/d, and 146.9 µg/d, respectively. The median UIC of baseline and follow-up was 155.7 (111.0–263.1) µg/L and 69.7(36.7–119.8) µg/L, respectively. The proportion of urinary iodine less than 50 g/L at the baseline and follow-up was 3.0 (0 ~ 8.9)% and 36.0 (33.1 ~ 38.9)%, respectively. Dietary iodine intake had a significant correlation with urine iodine. Six subjects (15.4%) had abnormal thyroid function. Three subjects (7.7%) had first-onset new nodules or enlarged solid nodules and the median UIC of these three subjects during the follow-up period was 39.8 µg/L, which was significantly lower than that of other subject (74.0 µg/L). T4 and T3 had a significant correlation with plasma iodine. The importance of monitoring and evaluating iodine nutrition of people consuming non-iodized salt should be stressed to prevent the potential poor iodine nutrition and iodine deficiency diseases.