A comparative study on iodine nutrition and thyroid function of different population in urban and rural areas of Wuwei, Gansu province

Abstract

To understand the iodine nutrition and thyroid function of different population in urban and rural areas of Gansu province and provide evidence for iodine supplementation. A cross-sectional survey was performed in urban and rural children, adults, pregnant women and breastfeeding women in Wuwei from April 2009 to January 2010. Urine and fasting blood samples were collected from the subjects. Urine iodine content was measured with arsenic cerium catalytic spectrophatometry. The thyroid-stimulating hormone (TSH) , free thyroid hormone (FT4) and three free triiodothyronine (FT3) were detected by using direct chemiluminescence immunoassy. Non parametric test was used to compare the urinary iodine and TSH group. t test was used to compare FT4, FT3. χ² test was used to compare the rate. The medians of urinary iodine level (µg/L) were 358.6, 189.0, 255.4 and 239.5 in urban children, adults, pregnant women and breastfeeding women and 387.6, 258.5, 172.8 and 215.3 in rural children, adults, pregnant women and breastfeeding women respectively. The median of urinary iodine of urban adults was significantly lower than that in rural adults (Z=-4.020, P=0.000) and the medians of urinary iodine level of urban pregnant women was higher than that in rural pregnant women (Z=1.424, P=0.035). The mean value of FT3 in rural pregnant women and breastfeeding women were higher than that in urban groups (t=-3.933, P=0.000; t=-2.259, P=0.026). The mean value of FT4 in urban adults was higher than that in rural adults (t=3.539, P=0.001). The positive rate of TGAb and TMAb in rural pregnant women and breastfeeding women were 43.6%, 56.4% and 33.3%, 35.6%, respectively, which were higher than those in urban groups. Subclinical hypothyroidism in all thyroid function disorders was common in all the groups. No statistical significant difference in all thyroid function disorders were found in different population. The iodine nutrition were in good status in both urban population and rural population, the children's iodine nutrition was surplus. Statistical differences existed in iodine nutrition status or thyroid hormone level between urban and rural adults, pregnant women and breastfeeding women.