Investigation of thyroid function abnormalities in children in high water iodine areas of Hebei province / 中华预防医学杂志

<p><b>OBJECTIVE</b>To understand the level of thyroid function and the prevalence of the thyroid diseases of children in high water iodine areas.</p><p><b>METHOD</b>Two primary schools were selected by purposive sampling from Haixing county, Hebei province in April 2010. A total of 371 children were selected from six classes by cluster sampling in the schools. Morning-urine and venous blood (5 ml) were collected to measure the levels of urinary iodine, free triiodothyronine (FT(3)), free thyroxine (FT(4)) and sensitive thyroid-stimulating hormone (sTSH) in serum and to evaluate the iodine status and thyroid function of children.</p><p><b>RESULTS</b>The median urinary iodine of the children was 1032.08 µg/L. Overall, 96.2% (357/371) of the children's urinary iodine were ≥ 300 µg/L and 68.5% (254/371) were ≥ 800 µg/L. The level of FT(3) and FT(4) were (6.28 ± 0.81) pmol/L and (16.37 ± 2.72) pmol/L, respectively. The median of sTSH was 4.01 mU/L. The FT(4) among boys ((16.63 ± 2.60) pmol/L) was significantly higher than that among girls ((15.99 ± 2.85) pmol/L) (P < 0.05). Overall, 44 subjects were diagnosed as thyroid disease (11.9%), 25 were subclinical hypothyroidism (57% of the total patients), 4 were hypothyroidism (9%), 10 were hyperthyroidism (23%) and 5 were subclinical hyperthyroidism (11%). In the urinary iodine of 200 - 799 µg/L, the prevalence of thyroid disease and hypothyroidism were 6.3% (7/111) and 14.6% (27/254), respectively. When urinary iodine ≥ 800 µg/L, the prevalence of thyroid diseases and hypothyroidism were 3.6% (4/111) and 8.3% (21/254), respectively.</p><p><b>CONCLUSION</b>Most of the children in high water iodine areas had excessive iodine intake. Levels of the children's thyroid hormone were within the normal range. The prevalence of thyroid disease were high, in these areas and the thyroid disease were mainly the subclinical hypothyroidism.</p>

Analysis of monitoring results of iodine deficiency disorders in Cangzhou city, Hebei province, from 2007 to 2009 / 中国地方病学杂志

Objective To understand the situation of iodine deficiency disorders of Cangzhou city, Hebei province, in order to provide the scientific basis for prevention and control of iodine deficiency disorders. Methods From 2007 to 2009, dynamic monitoring of iodine deficiency disorders was carried out in low iodized salt coverage places Hejian city and Xian county. Nine towns were randomly chosen in each county, 4 administrative villages were randomly selected in each town, 8 household salts were tested in each village. Every year, 1 - 3 copies of residents water samples were collected for determination of iodine; more than 100 students age 8 - 10 years old were checked the situation of goiter and urinary iodine, more than 40 students selected were measured iodine content of salt from their home; more than 50 women of childbearing age 18 - 40 years were tested of urinary iodine. Thyroid was examined with palpation; water iodine and urine iodine concentration were measured with arsenic-Ce catalytic spectrophotometry; salt iodine was detected by direct titration. Results From 2007 to 2009,median household salt iodine were 4.3,15.9,3.6,18.4,4.6,11.7 mg/kg in Hejian city and Xian county, respectively,iodized salt accounted for 34.03% (98/288), 78.82% (227/288), 29.86% (86/288), 84.72% (244/288), 37.15%(107/288),49.31% (142/288), respectively, the consuming rate of iodized salt were 27.08% (78/288),36.46%( 105/288 ), 28.13% (81/288 ), 49.31% ( 142/288 ), 37.15 % ( 107/288 ), 30.90% ( 89/288 ), respectively. Ten samples of drinking water were tested, water iodine were 5.5 - 34.4 μg/L. From 2007 to 2009, the goiter rate of students aged 8 - 10 years old was below 5%, the median of urinary iodine were 138.1,176.6,112.0 μg/L, ＜ 100 μg/L ratio were 31.6% ( 65/206 ), 25.0% ( 52/208 ) and 44.4% (91/205 ). The median of urinary iodine of child-bearing age women were 167.3,164.2,78.1 μg/L, ＜ 100 μg/L ratio were 28.7%(29/101 ), 19.2%(20/104) and 60.0%(60/100).Conclusions In areas with low coverage of iodized salt, iodine nutrition level are affected, the child-bearing age

Impact of iodine intake on thyroid diseases——A five-year prospective epidemiological study / 中华内分泌代谢杂志

Objective To evaluate the relationship between iodine intake level and the occurrence and development of thyroid diseases.Methods During the period of 1999-2004,a cross-sectional survey in 1999 and a 5-year follow-up survey were conducted in the 3 communities with different iodine intake levels in China:Panshan (mild deficiency),Zhangwu (more than adequate) and Huanghua (iodine excess).A total of 3 761 subjects were included in 1999 and 80.24% of them participated in the 5-year follow-up survey in 2004.The levels of serum thyroid hormones and thyroid autoantibodies were measured,and thyroid B ultrasound was performed.Results (1) The prevalence of overt hypothyroidism in 1999 in Zhangwu and Huanghua was 3.5 and 7.3 times,and that of subclinical hypothyroidism was 3.2 and 6.6 times as high as in Panshan,respectively.The 5-year cumulative incidence of subclinical hypothyroidism was 11.3 and 12.6 times as high as in Panshan,but no difference of incidence of overt hypothyroidism was found.(2) The prevalence of autoimmune thyroiditis (AIT) in 1999 in Zhangwu and Huanghua was 3.8 and 6.2 times,and the S-year cumulative incidence of AIT was 4.4 and 5.5 times as high as in Panshan.(3) During the 5-year follow-up period,the incidences of hypothyroidism in subjects with positive thyroid peroxidase antibody and euthyreidism in Zhangwu and Huanghua were 4.2 and 10.3 times as high as in Panshan.(4) No significant differences in both prevalence in 1999 and 5-year cumulative incidence of overt hyperthyroidism were found in the 3 communities.(5) The incidence of thyroid cancer was 19.37/100 000 per year in Huanghua,and all of the cases were papillary thyroid cancer,and no thyroid cancer was found in Zhangwu and Huanghua.Conclusion More than adequate or excessive dietary iodine intake may induce and promote the occurrence and development of hypothyroidism and AIT,therefore,median urinary iodine excretion (MUI)more than 200?g/L in the population appears not safe.The observation that a higher incidence of thyroid cancer occurred in the iodine excessive areas with MUI 600?g/L deserves further investigation.

A five-year follow-up study of hypothyroidism in areas with different iodine intakes / 中华内分泌代谢杂志

Objective To investigate epidemiologieal characteristics of hypothyroidism and factors influencing its outcome in the areas with different iodine intakes.Methods An epidemiologic follow-up study of thyroid diseases was performed in Panshan (iodine deficient),Zhangwu [mild iodine deficiency before universal salt iodination (USI) and more than adequate iodine intakes after USI ] and Huanghua ( iodine excessive) in China.A total of 3 761 subjects were investigated in 1999,and 3 018 (80.2% ) of them were followed up in 2004.FT_4,FT_3,TSH,thyroid autoantibodies and urinary iodine concentration were determined and thyroid B ultrasound was performed in all participants.Results Five-year cumulative incidence of overt hypothyroidism was 0.23%,0.47% and 0.35% in Panshan,Zhangwu and Huanghua,respectively.Twenty patients with autoimmune- induced overt hypothyroidism did not comply with the physician's orders to take thyroxine.Thyroid function spontaneously turned to normal in 55% of them,turned to subclinical hypothyroidism in 20% and maintained overt hypothyroidism in 25%.Five-year cumulative incidence of subclinical hypothyroidism in Zhangwu (2.60%) and Huanghua (2.89%) were significantly higher than that in Panshan(0.23% ) (both P＜0.01 ).One hundred patients with subclinical hypothyroidism were followed up,and 5% of them developed overt hypothyroidism,66% turned to euthyroidism and 29% maintained subclinical hypothyroidism.Raised serum TSH (＞6 mU/L) in the original survey ( OR = 3.4),positive thyroid autoantibodies in the follow-up study ( OR = 5.3 ) and more than adequate iodine supplementation in the mild iodine-deficient population ( OR = 8.0) were risk factors influencing outcome of subclinical hypothyroidism.Conclusion More than adequate iodine supplementation among a population in the mildly iodine-deficient area may increase the incidence of overt and subolinical hypothyroidism, and also influence outcome of subclinical hypothyroidism.