Iodine nutritional status and thyroid function of adults in urban and rural areas of Wuwei City Gansu Province

Abstract

Objective To study the iodine nutritional status and thyroid function of adults in urban and rural areas of Wuwei City Gansu Province. Methods A cross-sectional survey was performed in 200 adults aged 18 - 45 who had lived more than six months in Wuwei City from April 2009 to January 2010. A random urine and fasting blood samples were collected. Urinary iodine content was measured with arsenic cerium catalytic spectrophotometry. The thyroid-stimulating hormone (TSH), free thyroid hormone (FT4) and three free triiodothyronine(FT3) were quantified by direct chemiluminescence immunoassay. Thyroglobulin antibodies (TGAb) and thyroid microsomal antibodies (TMAb) were detected by radioimmunoassay. Results A total of 99 and 98 copies of urine samples of urban and rural groups were tested, respectively. The median of urinary iodine of urban and rural groups was 189.0 and 258.2 μg/L, respectively, and rural group was higher than urban group (Z =- 4.020,P < 0.01). A total of 104 and 95 copies of blood samples of urban and rural groups were detected; mean value of FT4 in urban group[(16.8 ± 3.0)pmol/L] was higher than that of rural group[(15.4 ± 2.4)pmol/L,t = 3.539,P < 0.01]. The positive rates of TGAb of urban and rural groups were 11.5% (12/104) and 15.8% (15/95), respectively; the positive rates of TMAb of urban and rural groups were 13.5% (14/104) and 14.7% (14/95), respectively; the positive rates of TGAb of male and female were 5.5% (6/109) and 23.3% (21/90), respectively; the positive rates of TMAb of male and female were 6.4% (7/109) and 23.3% (21/ 90), respectively. The positive rates of TGAb and TMAb were lower in male than in female(χ2 = 13.362, 11.661, all P < 0.01). The rates of thyroid function disorders of urban and rural groups were 16.3% (17/104) and 8.4% (8/95), of male and female 11.9% (13/109) and 13.3% (12/90), respectively. Subclinical hypothyroidism in all thyroid function disorders was the most common, which was 14.4% (15/104) and 7.4% (7/95) in urban and rural groups, 11.0% (12/109) and 11.1% (10/90) in male and female, respectively. Conclusions Iodine nutrition level is appropriate for adults in urban areas, but in rural areas iodine nutrition is high or excessive; subclinical hypothyroidism in all thyroid function disorders is the most common; we should be concerned about the risk of iodine overdose, especially the risk of illness in women. Key words: Adult; Iodine; Thyroid gland