Xiaohui Yu

Bio: Xiaohui Yu is an academic researcher from Texas A&M University. The author has contributed to research in topics: Thyroid & Thyroid function. The author has an hindex of 4, co-authored 7 publications receiving 1041 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.

Abnormalities of maternal thyroid function during pregnancy affect neuropsychological development of their children at 25–30 months

Abstract: Summary Objective To examine the relationship between specific thyroid abnormalities (subclinical hypothyroidism, hypothyroxinaemia or elevated thyroid peroxidase antibody titres) in women during pregnancy and the subsequent neuropsychological development of their offspring. Design/Patients Serum was collected from 1268 women at 16–20 weeks of gestation and thyroid stimulating hormone (TSH), total thyroxine (tT4), free thyroxine (fT4), and Thyroid peroxidase antibodies (TPOAb) levels were measured. Thyroid function reference ranges specific for pregnancy were used to screen for thyroid abnormalities. Patients with isolated subclinical hypothyroidism (18 cases), hypothyroxinaemia (19 cases), and those who were euthyroid patients with elevated titres of TPOAb (34 cases) were identified. One hundred and forty-two euthyroid and TPOAb-negative women matched for gestational age from the same cohort were selected as controls. Measurements Intellectual and motor development score evaluations were performed on the children from the pregnancies at 25–30 months of age. Results Children of women with subclinical hypothyroidism, hypothyroxinemia and elevated TPOAb titres had mean intelligence scores 8·88, 9·30 and 10·56 points lower than those of the control group (P = 0·008, P = 0·004 and P = 0·001, respectively); mean motor scores were 9·98, 7·57 and 9·03 points lower than those of the controls [P < 0·001, P = 0·007 and P < 0·001, respectively (t-test)]. Unconditional multivariate logistic regression analysis showed that increased maternal serum TSH, decreased maternal serum tT4, and elevated maternal TPOAb titres were separately associated with lower intelligence scores (ORs 15·63, 12·98, and 6·69, respectively) and poorer motor scores (ORs 9·23, 5·52, and 8·25, respectively). Conclusions Intellectual and motor development of children at 25–30 months of age is separately associated with abnormalities of maternal thyroid at 16–20 weeks gestation. Maternal subclinical hypothyroidism, hypothyroxinaemia or euthyroidism with elevated TPOAb titres were all statistically significant predictors of lower motor and intellectual development at 25–30 months.

The prevalence of thyroid disorders during early pregnancy in China: the benefits of universal screening in the first trimester of pregnancy

Abstract: Context Maternal thyroid disorders during early pregnancy can influence pregnancy outcome and fetal development. The recent Endocrine Society Clinical Practice Guideline recommends a case-finding approach in which pregnant women who are at high risk for developing thyroid disease are tested. Objective The purpose of this study was to use the first trimester-specific reference intervals of thyroid-related hormones to explore the prevalence of thyroid dysfunction during early pregnancy and to analyze effectiveness of different screening strategies. Design A multicenter cohort study. Method A total of 2899 pregnant women were enrolled in this study during their first trimester of gestation. Levels of TSH, free thyroxine, free triiodothyronine, and thyroid peroxidase antibodies (TPOAb) were measured and thyroid disorders of pregnant women were diagnosed based on the first trimester-specific reference intervals. Results The prevalence of hypothyroidism was significantly higher in the high-risk group than in the non-high-risk group (10.9 vs 7.0%, χ²=7.1, P = 0.008). The prevalence of hyperthyroidism was not significantly different between the high-risk group and the non-high-risk group (2.7 vs 1.6%, χ²=2.27, P=0.13). Elevated levels of TPOAb and a personal history of thyroid disease increased the risk of thyroid dysfunction. Conclusions A case-finding strategy for screening thyroid function in the high-risk group would miss about 81.6% pregnant women with hypothyroidism and 80.4% pregnant women with hyperthyroidism.

Chronic iodine excess does not increase the incidence of hyperthyroidism: a prospective community-based epidemiological survey in China.

Abstract: Objective: An increasing incidence of hyperthyroidism has been observed when iodine supplementation has been introduced to an iodine-deficient population. Moreover, the influence of chronic more than adequate or excessive iodine intake on the epidemiological features of hyperthyroidism has not been widely and thoroughly described. To investigate the influences of different iodine intake levels on the incidence of hyperthyroidism, we conducted a prospective community-based survey in three communities with mild-deficient, more than adequate (previously mild deficient iodine intake), and excessive iodine intake. Subjects and methods: In three rural Chinese communities, a total of 3761 unselected inhabitants aged above 13 years participated in the original investigation and 3018 of them received identical examinations after 5 years. Thyroid function, levels of thyroid peroxidase antibody (TPOAb), thyroglobulin antibody and urinary iodine excretion were measured and thyroid ultrasound examination was also performed. Results: In three communities, median urinary iodine excretion was 88, 214, and 634 mg/l (P!0.05) respectively. The cumulative incidence of hyperthyroidism was 1.4, 0.9, and 0.8% (PO0.05) respectively. Autoimmune hyperthyroidism was predominant in thyroid hyperfunction in all the three cohorts. Either positive TPOAb (O50 U/ml) or goiter in original healthy participants was associated with the occurrence of unsuspected hyperthyroidism in 5 years (logistic regression, ORZ4.2 (95% CI 1.7‐8.8) for positive TPOAb, ORZ3.1 (95% CI 1.4‐6.8) for goiter). Conclusion: Iodine supplementation may not induce an increase in hyperthyroidism in a previously mildly iodine-deficient population. Chronic iodine excess does not apparently increase the risk of autoimmune hyperthyroidism, suggesting that excessive iodine intake may not be an environmental factor involved in the occurrence of autoimmune hyperthyroidism.

Gender-Specific Associations Between Metabolic Disorders and Thyroid Nodules: A Cross-Sectional Population-Based Study From China.

Abstract: BACKGROUND Metabolic disorders (MDs) and the Metabolic Syndrome (MetS) may be associated with thyroid diseases. The aim of this study was to investigate the relationship between MDs and various types of thyroid nodules (TNs), according to gender. METHODS We analyzed cross-sectional data from the Thyroid Disorders, Iodine Status, and Diabetes Epidemiological (TIDE) survey in China. A total of 56,729 subjects aged ≥18 years were included. Thyroid gland morphology was assessed by thyroid standardized ultrasonography. A multivariate logistic regression model was used to explore the odds ratio (OR) and 95% confidence intervals (95%CI) for any associations between MDs and TNs. Subgroup analyses were conducted according to gender and TN type (solitary, S-TN; multiple, M-TNs).. RESULTS The prevalence of TNs was increased in several MDs, and was higher in women than men regardless of whether they suffered from MDs [22.0% 95%CI (21.6%, 22.5%) vs. 15.7% 95%CI (15.3%, 16.7%), p<0.001]. TNs were associated with the presence of MDs [OR=1.189, 95%CI (1.107, 1.278), p<0.001], hypercholesterolemia [OR=1.235, 95%CI (1.177, 1.296), p<0.001], high LDL-C [OR=1.249, 95%CI (1.186, 1.316), p<0.001], and hyperuricemia [OR=1.206, 95%CI (1.126, 1.293), p<0.001]. MDs and MetS were respectively significantly associated with TNs, S-TNs and M-TNs in men, while MDs were significantly associated with the three TN profiles in women. With respect to dyslipidemia, hypercholesterolemia and high LDL-C had the strongest association with TNs, while hypertriglyceridemia had no effect. CONCLUSIONS TNs (especially M-TNs) may be associated with MDs and their various components and there appear to be some gender-specific associations.

2017 Guidelines of the American Thyroid Association for the Diagnosis and Management of Thyroid Disease During Pregnancy and the Postpartum

Abstract: Background: Thyroid disease in pregnancy is a common clinical problem. Since the guidelines for the management of these disorders by the American Thyroid Association (ATA) were first published in 2...

Management of Thyroid Dysfunction during Pregnancy and Postpartum: An Endocrine Society Clinical Practice Guideline

Abstract: Objective: The aim was to update the guidelines for the management of thyroid dysfunction during pregnancy and postpartum published previously in 2007. A summary of changes between the 2007 and 2012 version is identified in the Supplemental Data (published on The Endocrine Society's Journals Online web site at http://jcem.endojournals.org). Evidence: This evidence-based guideline was developed according to the U.S. Preventive Service Task Force, grading items level A, B, C, D, or I, on the basis of the strength of evidence and magnitude of net benefit (benefits minus harms) as well as the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) system to describe both the strength of recommendations and the quality of evidence. Consensus Process: The guideline was developed through a series of e-mails, conference calls, and one face-to-face meeting. An initial draft was prepared by the Task Force, with the help of a medical writer, and reviewed and commented on by members of The Endocri...

Guidelines of the American Thyroid Association for the Diagnosis and Management of Thyroid Disease During Pregnancy and Postpartum The American Thyroid Association Taskforce on Thyroid Disease During Pregnancy and Postpartum

Abstract: Pregnancy has a profound impact on the thyroid gland and thyroid function. The gland increases 10% in size during pregnancy in iodine-replete countries and by 20%– 40% in areas of iodine deficiency. Production of thyroxine (T4) and triiodothyronine (T3) increases by 50%, along with a 50% increase in the daily iodine requirement. These physiological changes may result in hypothyroidism in the later stages of pregnancy in iodine-deficient women who were euthyroid in the first trimester. The range of thyrotropin (TSH), under the impact of placental human chorionic gonadotropin (hCG), is decreased throughout pregnancy with the lower normal TSH level in the first trimester being poorly defined and an upper limit of 2.5 mIU/L. Ten percent to 20% of all pregnant women in the first trimester of pregnancy are thyroid peroxidase (TPO) or thyroglobulin (Tg) antibody positive and euthyroid. Sixteen percent of the women who are euthyroid and positive for TPO or Tg antibody in the first trimester will develop a TSH that exceeds 4.0 mIU/L by the third trimester, and 33%–50% of women who are positive for TPO or Tg antibody in the first trimester will develop postpartum thyroiditis. In essence, pregnancy is a stress test for the thyroid, resulting in hypothyroidism in women with limited thyroidal reserve or iodine deficiency, and postpartum thyroiditis in women with underlying Hashimoto’s disease who were euthyroid prior to conception. Knowledge regarding the interaction between the thyroid and pregnancy/the postpartum period is advancing at a rapid pace. Only recently has a TSH of 2.5 mIU/L been accepted as the upper limit of normal for TSH in the first trimester. This has important implications in regards to interpretation of the literature as well as a critical impact for the clinical diagnosis of hypothyroidism. Although it is well accepted that overt hypothyroidism and overt hyperthyroidism have a deleterious impact on pregnancy, studies are now focusing on the potential impact of subclinical hypothyroidism and subclinical hyperthyroidism on maternal and

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...