PREVALENCE OF NONTOXIC NODULAR GOITER AFTER A NEARLY TWO-DECADE UNIVERSAL SALT IODIZATION IN A LITTORAL REGION OF SHANDONG PROVINCE, CHINA

Introduction. With the introduction of iodized salt, more and more people are exposed to iodine sufficiency in some regions. The purpose of this study was to investigate the prevalence of nontoxic nodular goiter (NTNG) in the littoral region with high iodine supply after a nearly two decade universal salt iodization. Subjects and Methods. Eight hundred and thirty-five participants (from 25 similar to 65 years; males 421 and females 414) were invited for the study from Huan-cui District of Weihai City, Shandong Province from January 2013 to September 2014. All participants were inspected and diagnosed by endocrinologists according to the thyroid function tests and the thyroid gland imaging. After the normal diet of three days, the urine samples of the participants were collected between 8:00AM and 9:00AM and the urinary iodine (UI) concentrations were analyzed using Urinary Iodide Test Kit. Results. The overall prevalence of NTNG in the region was 40.1%, and different prevalence occurred in the different age ranges (p<0.01). The prevalence of NTNG was 32.51%, 37.44%, 49.70%, 58.57 and 74.77% in the age group of <= 30, 31-40, 41-50, 51-60 and >60 years, respectively. Meanwhile, the prevalence of NTNG in women (42.08%) was higher than that in men (34.29%, p<0.05). The median of UI concentrations were 139.4 mu g/L and 101.5 mu g/L for the group with NTNG and without NTNG, respectively (p<0.01). However, there was no significant difference in UI concentrations among the groups with different age ranges (p>0.05), and statistical difference was not observed for UI concentrations between women and men (p>0.05). Intriguingly, higher UI concentrations were found in the group with larger thyroid size (p<0.01). Conclusion. The iodine excess can lead to the high occurrence of nodular goiter in the littoral region, and individual UI concentration detection is recommended for the iodine nutritional status analysis among normal people when Universal Salt Iodization (USI) continues to be implemented in the region.