Xiao-chun Teng

Bio: Xiao-chun Teng is an academic researcher. The author has contributed to research in topics: Thyroid & Thyroid peroxidase. The author has an hindex of 3, co-authored 3 publications receiving 580 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.

An epidemiological study on the relationship between selenium and thyroid function in areas with different iodine intake

Abstract: Objective To investigate the relationship between selenium status and thyroid dysfunction in 3 areas with different iodine intake.Methods An epidemiological research was performed in the rural communities of Panshan County (iodine-deficient area) and Zhangwu County (iodine-sufficient area), Liaoning Province, and Huanghua County, Hebei Province (iodine-excessive area).Serum selenium, TSH, FT3 and FT4 levels were examined in 329 patients with thyroid dysfunction (including clinical hypothyroidism, subclinical hypothyroidism, clinical hyperthyroidism and subclinical hyperthyroidism) and 183 normal inhabitants.Results The median serum selenium concentrations in Panshan, Zhangwu and Huanghua were 91.4, 89.1, and 83.2 μg/L respectively.There was no difference in serum selenium levels between the patients with subclinical hypothyroidism, clinical hypothyroidism, and clinical hyperthyroidism and their normal controls.The median serum selenium concentration of the subclinical hyperthyroidism patients was 82.6 μg/L, significantly lower than that of the normal controls (87.3 μg/L). The FT3/FT4 ratio was decreased, the FT4 level was increased in the subclinical hyperthyroidism patients in comparison with the normal controls, and no significant difference in FT3 level was found between them.No significant effect of sex and age was found on serum selenium level of normal inhabitants.In normal controls serum selenium was inversely correlated with serum TSH level, and the subjects with serum selenium ≤80 μg/L had the median TSH level of 2.10 mU/L, markedly higher than that of the subjects with the serum selenium of 80～100 μg/L (1.29 mU/L) and that of the subjects with the serum selenium of 100～120 μg/L (1.28 mU/L).For thethyroid dysfunction patients with positive thyroid auto-antibody (TPOAb) in Zhangwu County, the serum selenium was negatively associated with TPOAb level.The serum selenium level of the TPOAb highly positive group (TPOAb 600 IU/ml)was 83.6 IU/ml, significantly lower than those of the TPOAb lowly positive group and TPOAb moderately positive group (83.6, 92.9 and 95.6 μg/L respectively). Conclusion No obvious effect of selenium status is found on the development of thyroid dysfunction in these three areas.But selenium deficiency can impair thyroid function by means of disturbing thyroid hormone metabolism and decreasing antioxidant ability of the thyroid.

[Correlation between serum thyroglobulin and thyroid stimulating hormone in populations with non-toxic goiter].

Abstract: OBJECTIVE: To investigate the correlation between serum thyroglobulin (Tg) and thyroid stimulating hormone (TSH) in populations with non-toxic goiter. METHODS: Thyroid ultrasonography was conducted, and determination of serum triiodothyronine (FT3), thyroxin (FT4), Tg, thyroid peroxidase antibody (TPOAb), thyroglobulin antibody (TGAb) and TSH, and urine iodine were carried out among 609 persons with an average age of 35.4 in Panshan county, a mild iodine-deficient area in Liaoning province, and 1136 persons aged 39.1 on average in Zhangwu county, an iodine sufficient area in Liaoning province, totally 2 320 persons. RESULTS: The serum TSH levels of the populations with diffuse and nodular goiter in Panshan county were (0.11 +/- 0.08) mU/L and (0.90 +/- 0.10) mU/L, significantly higher than those of the normal population in the same areas (1.33 +/- 0.04) mU/L, both P < 0.01. The serum TSH levels of the populations with diffuse and nodular goiter in Zhangwu county were (1.29 +/- 0.13) mU/L and (0.89 +/- 0.14) mU/L, significantly higher than those of the normal population in the same areas (1.74 +/- 0.04) mU/L, both P < 0.01. The serum TSH level of normal population in iodine deficient area was significantly lower than that of normal population in iodine sufficient area (P < 0.01). The serum TSH level of the normal population in Panshan County was significantly lower than that of the normal population in Zhangwu County (P < 0.01). The serum Tg level of the populations with diffuse and nodular goiter in Panshan county were (12.0 +/- 1.21) ng/L and (50.1 +/- 12.20) ng/L, significantly higher than that of the normal population in the same area (9.1 +/- 2.44) ng/L, P < 0.05 and P < 0.01. The serum Tg level of the populations with diffuse and nodular goiter in Zhangwu county were (12.4 +/- 2.11) ng/L and (61.2 +/- 11.86) ng/L, significantly higher than that of the normal population in the same area (7.7 +/- 2.3) ng/L, P < 0.05 and P < 0.01. The Tg level of the normal population in Panshan County was significantly higher than that of the normal population in Zhangwu county (P < 0.01). The Tg level was positively correlated with the thyroid volume in the nodular goiter population. CONCLUSION: The occurrence of goiter is not directly related to TSH stimulation in mild iodine deficient area. Nontoxic goiter shows a thyroid autonomic function. The major cause of high serum Tg in nodular goiter may be the leakage of Tg into blood circulation caused by degeneration of large colloid follicles and destruction of follicular architecture, not the volume increase of thyroid and its autonomic function.

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.