Wei-bo Wang

Bio: Wei-bo Wang is an academic researcher from China Medical University (PRC). The author has contributed to research in topics: Thyroid & Thyroid peroxidase. The author has an hindex of 7, co-authored 10 publications receiving 716 citations.

Effect of iodine intake on thyroid diseases in China.

Abstract: Background Iodine is an essential component of thyroid hormones; either low or high intake may lead to thyroid disease. We observed an increase in the prevalence of overt hypothyroidism, subclinical hypothyroidism, and autoimmune thyroiditis with increasing iodine intake in China in cohorts from three regions with different levels of iodine intake: mildly deficient (median urinary iodine excretion, 84 μg per liter), more than adequate (median, 243 μg per liter), and excessive (median, 651 μg per liter). Participants enrolled in a baseline study in 1999, and during the five-year follow-up through 2004, we examined the effect of regional differences in iodine intake on the incidence of thyroid disease. Methods Of the 3761 unselected subjects who were enrolled at baseline, 3018 (80.2 percent) participated in this follow-up study. Levels of thyroid hormones and thyroid autoantibodies in serum, and iodine in urine, were measured and B-mode ultrasonography of the thyroid was performed at baseline and follow-up. Results Among subjects with mildly deficient iodine intake, those with more than adequate intake, and those with excessive intake, the cumulative incidence of overt hypothyroidism was 0.2 percent, 0.5 percent, and 0.3 percent, respectively; that of subclinical hypothyroidism, 0.2 percent, 2.6 percent, and 2.9 percent, respectively; and that of autoimmune thyroiditis, 0.2 percent, 1.0 percent, and 1.3 percent, respectively. Among subjects with euthyroidism and antithyroid antibodies at baseline, the five-year incidence of elevated serum thyrotropin levels was greater among those with more than adequate or excessive iodine intake than among those with mildly deficient iodine intake. A baseline serum thyrotropin level of 1.0 to 1.9 mIU per liter was associated with the lowest subsequent incidence of abnormal thyroid function. Conclusions More than adequate or excessive iodine intake may lead to hypothyroidism and autoimmune thyroiditis.

Influence of iodine on the reference interval of TSH and the optimal interval of TSH: results of a follow-up study in areas with different iodine intakes.

Abstract: Summary Objective The aim of the present study was to evaluate whether the status of iodine nutrition influences the TSH concentration in a selected Chinese reference population according to the criteria proposed by National Academy of Clinical Biochemistry (NACB) and regular thyroid ultrasonography, to establish a new reference interval of TSH based on the wide variation of iodine nutrition in populations, and to identify an optimal interval of TSH by following up the cohort with normal TSH concentrations at baseline. Design The study was conducted in Panshan, Zhangwu and Huanghua, the regions with mildly deficient, more than adequate and excessive iodine intake, respectively. Of the 3761 unselected subjects who were enrolled at baseline, 2237 met the criteria for a reference population. Of 3048 subjects with normal serum TSH at baseline, 2727 (80·0%) participated in the 5-year follow-up study. TSH and thyroid autoantibodies in serum and iodine in urine were measured, and B-mode ultrasonography of the thyroid was performed. Results In the reference population, there was a urinary iodine-related increment of serum TSH levels (r = 0·21, P = 0·000), and the mean levels of TSH in Panshan, Zhangwu and Huanghua were 1·15, 1·28 and 1·93 mIU/l, respectively (P = 0·000), corresponding to the rising regional iodine intake. Based on the overall data, we obtained a reference interval of 0·3–4·8 mIU/l. TSH concentrations obtained in the follow-up study correlated well with those at baseline (r = 0·58, P = 0·000). A baseline serum TSH > 1·9 mIU/l was associated with an increased incidence of development of supranormal TSH and a baseline serum TSH < 1·0 mIU/l was associated with an increased incidence of subnormal TSH development. Conclusions Iodine nutrition is an important factor associated with TSH concentration even in the rigorously selected reference population. Baseline TSH of 1·0–1·9 mIU/l is an optimal interval with the lowest incidence of abnormal TSH in 5 years.

Effect of different iodine intake on schoolchildren's thyroid diseases and intelligence in rural areas.

Abstract: Background Reports are increasingly appearing on the side effects caused by excessive iodine intake. Our objective was to find out whether iodine excess would impair the thyroid function and intelligence of schoolchildren in rural areas of China. Methods A comparative epidemiological study was made on thyroid function and intelligence of the schoolchildren in the areas of low, moderate or excessive intake of iodine. In the area of low intake of iodine (Panshan, Liaoning province, median urinary iodine (MUI) was 99 microg/L), of moderate intake of iodine (Zhangwu, Liaoning Province, MUI was 338 microg/L) and of excessive intake of iodine (Huanghua, Hebei Province, MUI was 631 microg/L). The numbers of schoolchildren from each area selected to take part in a Chinese version of Raven's Test were 190, 236 and 313, respectively, and then 116, 110 and 112 of them were tested for thyroid function, thyroid autoantibody (TAA) and urinary iodine (UI). Results There were no significant differences in the incidences of overt hyperthyroidism, subclinical hyperthyroidism and overt hypothyroidism in Panshan, Zhangwu and Huanghua. But significant differences were found in the incidences of subclinical hypothyroidism (P = 0.001) in these three areas. The incidences of subclinical hypothyroidism in Huanghua and Zhangwu were 4.76 and 3.37 times higher than that in Panshan. TAA were negative in all the schoolchildren with subclinical hypothyroidism except for one. No significant difference was found among the rates of thyroid peroxidase antibody (TPOAb) and thyroglobulin antibody (TGAb) in these three areas. Mean serum thyroglobulin (TG) value of Huanghua was markedly higher than those of the other two (P = 0.02). Mean serum TG value of Zhangwu was higher than that of Panshan but the difference was not significant. Mean IQ value of the schoolchildren in Huanghua was markedly higher than that for Zhangwu (P = 0.001). Mean IQ value of the schoolchildren in Panshan was lower than that of Huanghua and higher than that of Zhangwu but, again, the differences were not significant. Conclusions The increase of iodine intake may increase the risk for schoolchildren of subclinical hypothyroidism. In the area of iodine excess, most of the subclinical hypothyroidism cases are not of autoimmune origin. No obvious effect of excess iodine was found on mental development of schoolchildren.

Safe Range of Iodine Intake Levels: A Comparative Study of Thyroid Diseases in Three Women Population Cohorts with Slightly Different Iodine Intake Levels

Abstract: Iodine excess may lead to thyroid diseases. Our previous 5-year prospective survey showed that the prevalence and incidence of hypothyroidism or autoimmune thyroiditis increased with iodine intake. The aim of the present study was to investigate the optimal range of iodine intake by comparing the prevalence of thyroid diseases in three areas with slightly different levels of iodine intake. In 2005, 778 unselected women subjects from three areas with different iodine intake levels were enrolled. Levels of serum thyroid hormones, thyroid autoantibodies, and urinary iodine were measured, and thyroid B ultrasounds were performed. Among the subjects with mildly deficient iodine intake, those with adequate intake, and those with more than adequate intake, the prevalence of clinical and subclinical hypothyroidism was 0, 1.13, and 2.84%, respectively (P = 0.014); that of thyroid goiter was 24.88, 5.65, and 11.37%, respectively (P < 0.001); that of serum thyrotropin values was1.01, 1.25, and 1.39 mIU/l, respectively; and that of serum thyrotropin/thyroglobulin ratio was 7.98, 6.84, and 5.11, respectively (P < 0.001). In conclusion, median urinary iodine 100~200 μg/l may reflect the safe range of iodine intake levels. Serum thyrotropin/thyroglobulin ratio might be a better index of evaluating iodine status.

The clinical significance of subclinical thyroid dysfunction.

Abstract: Subclinical thyroid disease (SCTD) is defined as serum free T4 and free T3 levels within their respective reference ranges in the presence of abnormal serum TSH levels. SCTD is being diagnosed more frequently in clinical practice in young and middle-aged people as well as in the elderly. However, the clinical significance of subclinical thyroid dysfunction is much debated. Subclinical hyper- and hypothyroidism can have repercussions on the cardiovascular system and bone, as well as on other organs and systems. However, the treatment and management of SCTD and population screening are controversial despite the potential risk of progression to overt disease, and there is no consensus on the thyroid hormone and thyrotropin cutoff values at which treatment should be contemplated. Opinions differ regarding tissue effects, symptoms, signs, and cardiovascular risk. Here, we critically review the data on the prevalence and progression of SCTD, its tissue effects, and its prognostic implications. We also examine t...

Very high prevalence of thyroid nodules detected by high frequency (13 MHz) ultrasound examination.

Abstract: Background The prevalence of thyroid nodules in a healthy population is high: in the German Papillon study, nationwide ultrasound screening of more than 90 000 people using 7·5 MHz scanners revealed the presence of thyroid nodules in 33% of the normal population. A study employing more sensitive 13 MHz scanners has not been conducted so far. Materials and methods Six hundred and thirty-five consecutive patients (33% female, 67% male, mean 56·7 years) presenting for a preventive health check up underwent ultrasound screening of the thyroid gland (Siemens Acuson Antares, 13 MHz-linear scanner, B-mode and Power mode) and measurement of the basal TSH (thyroid stimulating hormone) value. Size and degree of vascularization of the thyroid gland and of nodules were determined and analysed retrospectively. Results In 432 of 635 patients, thyroid nodules could be detected with an increasing incidence with age, in 338 without goiter. Mean thyroid size was 12·3 mL for women and 20·5 mL for men correlating strongly with body weight. Fifty-three percentage of the nodules were smaller than 5 mm. Incidence of thyroid dysfunction was only 4%. No cancerous lesions could be found. Conclusions Using the 13 MHz technology, we found a substantially higher prevalence of thyroid nodules (68%) than the Papillon study (33%). Even if our population is older than in Papillon, the difference remains in comparable age groups. This is due to the higher sensitivity of 13 MHz scanning. Our study underlines the clinical significance of iodine deficiency and should renew the discussion on routine iodine supplementation.

Effect of iodine intake on thyroid diseases in China.

Abstract: Background Iodine is an essential component of thyroid hormones; either low or high intake may lead to thyroid disease. We observed an increase in the prevalence of overt hypothyroidism, subclinical hypothyroidism, and autoimmune thyroiditis with increasing iodine intake in China in cohorts from three regions with different levels of iodine intake: mildly deficient (median urinary iodine excretion, 84 μg per liter), more than adequate (median, 243 μg per liter), and excessive (median, 651 μg per liter). Participants enrolled in a baseline study in 1999, and during the five-year follow-up through 2004, we examined the effect of regional differences in iodine intake on the incidence of thyroid disease. Methods Of the 3761 unselected subjects who were enrolled at baseline, 3018 (80.2 percent) participated in this follow-up study. Levels of thyroid hormones and thyroid autoantibodies in serum, and iodine in urine, were measured and B-mode ultrasonography of the thyroid was performed at baseline and follow-up. Results Among subjects with mildly deficient iodine intake, those with more than adequate intake, and those with excessive intake, the cumulative incidence of overt hypothyroidism was 0.2 percent, 0.5 percent, and 0.3 percent, respectively; that of subclinical hypothyroidism, 0.2 percent, 2.6 percent, and 2.9 percent, respectively; and that of autoimmune thyroiditis, 0.2 percent, 1.0 percent, and 1.3 percent, respectively. Among subjects with euthyroidism and antithyroid antibodies at baseline, the five-year incidence of elevated serum thyrotropin levels was greater among those with more than adequate or excessive iodine intake than among those with mildly deficient iodine intake. A baseline serum thyrotropin level of 1.0 to 1.9 mIU per liter was associated with the lowest subsequent incidence of abnormal thyroid function. Conclusions More than adequate or excessive iodine intake may lead to hypothyroidism and autoimmune thyroiditis.