Low Thyroid-stimulating Hormone Levels Are Associated With Annoying Tinnitus in Adult Women: Korea National Health and Nutrition Examination Surveys

Associations between short-term exposure to air pollution and thyroid function in a representative sample of the Korean population

BACKGROUND

Disruption of thyroid function can profoundly affect various organ systems. However, studies on the association between air pollution and thyroid function are relatively scarce and most studies have focused on the long-term effects of air pollution among pregnant women.

OBJECTIVES

This study aimed to explore the associations between short-term exposure to air pollution and thyroid function in the general population.

METHODS

Data from the Korea National Health and Nutrition Examination Survey (2013-2015) were analyzed (n = 5,626). Air pollution concentrations in residential addresses were estimated using Community Multiscale Air Quality models. The moving averages of air pollution over 7 days were set as exposure variables through exploratory analyses. Linear regression and quantile g-computation models were constructed to assess the effects of individual air pollutants and air pollution mixture, respectively.

RESULTS

A 10-ppb increase in NO2 (18.8-μg/m3 increase) and CO (11.5-μg/m3 increase) was associated with 2.43% [95% confidence interval (CI): 0.42, 4.48] and 0.19% (95% CI: 0.01, 0.36) higher thyroid-stimulating hormone (TSH) levels, respectively. A 10-μg/m3 increase in PM2.5 and a 10-ppb increase in O3 (19.6-μg/m3 increment) were associated with 0.87% (95% CI: 1.47, -0.27) and 0.59% (95% CI: 1.18, -0.001) lower free thyroxine (fT4) levels, respectively. A simultaneous quartile increase in PM2.5, NO2, O3, and CO levels was associated with lower fT4 but not TSH levels.

CONCLUSIONS

As the subtle changes in thyroid function can affect various organ systems, the present results may have substantial public health implications despite the relatively modest effect sizes. Because this was a cross-sectional study, it is necessary to conduct further experimental or repeated-measures studies to consolidate the current results.

Benign paroxysmal positional vertigo: is hypothyroidism a risk factor for recurrence?

OBJECTIVE

To investigate the relationship between risk of Benign Paroxysmal Positional Vertigo (BPPV) recurrence and hypothyroidism treated with hormone replacement therapy (HRT).

METHODS

797 patients with idiopathic BPPV were divided into two groups: 250 patients with recurrence of BPPV (R-BPPV) and 547 patients without recurrence (NR-BPPV). Regarding patients with thyroid disease on HRT, we collected serum test results of thyroid-stimulating hormone (TSH), free triiodothyronine f-T3, free thyroxine f-T4, thyroglobulin antibodies (TG-Ab) and thyroid peroxidase antibodies (TPO-Ab).

RESULTS

Hypothyroidism in long-term HRT was found in 61/250 (24.4%) patients of the R-BPPV group vs 79/547 (14.4%) of the NR-BPPV-group (p = 0.0006). Hashimoto thyroiditis (HT) was associated with recurrence (p < 0.0001). A significant correlation was found between recurrence and level of serum TPO-Ab (p = 0.0117) and TG-Ab (p = 0.0025), but not with mean serum TSH, f-T3 and f-T4.

CONCLUSIONS

We assume that patients with hypothyroidism in HRT have an increased risk of BPPV recurrence, which is particularly strong for patients with HT and positive thyroid antibodies, suggesting an association between autoimmunity and recurrent vertigo.

Association Between Body Mass Index and Female Infertility in the United States: Data from National Health and Nutrition Examination Survey 2013–2018

Purpose

This study aimed to investigate the effects of body mass index (BMI) on infertility in women of childbearing age.

Patients and Methods

We performed a cross-sectional study using data from 3624 participants from the National Health and Nutrition Examination Survey (NHANES). We used BMI and fertility status in the survey as independent and dependent variables, respectively. We evaluated their relationship and used smoothed curve fitting and multivariate logistic regression analysis as well as a generalized additive model (GAM) to determine the effect of BMI.

Results

Logistic regression model analysis linked BMI and infertility after adjusting for potential confounders OR 1.03, 95%Cl: 1.02–1.05). There was a non-linear relationship between BMI and infertility, with each unit increase in BMI reducing the risk of infertility by 33% when BMI was <19.5 kg/m². In contrast, when BMI ≥19.5 kg/m², each unit increase in BMI predicted a 3% increase in the risk of infertility.

Conclusion

The relationship between infertility and BMI presented a U-shaped curve. Therefore, a BMI that lay at the extremes of the spectrum tended to predict infertility. We believe that this study will support the maintenance of suitable BMI levels in women preparing for pregnancy.

Increased Incidence of Tinnitus Following a Hyperthyroidism Diagnosis: A Population-Based Longitudinal Study

BACKGROUND

An association between thyroid disease and tinnitus has been described previously but further longitudinal, population-based studies are limited.

OBJECTIVE

To investigate the incidence of tinnitus in patients with hyperthyroidism in a national sample, and to identify risk level and associated factors for tinnitus in hyperthyroidism patients.

DESIGN

Retrospective cohort study. Patient data were collected from the Longitudinal Health Insurance Database (LHID 2000), which includes national claims data of patient expenditures for admissions or ambulatory care from 1996 to 2011.

SETTING

Taiwan hospitals and clinics providing healthcare nationwide.

PARTICIPANTS

Patients aged 20 years and older with newly diagnosed hyperthyroidism (ICD-9-CM code 242) between 2000-2010 were selected as the study cohort. Hyperthyroidism patient cohort were identified from the LHID2000. Those with tinnitus history (ICD-9-CM code 388.3) before the index date (first hyperthyroidism diagnosis), younger than 20 years, and with incomplete demographic data were excluded. The non-hyperthyroidism cohort included patients with no history of hyperthyroidism and no documented tinnitus.

MAIN OUTCOMES AND MEASURES

Incidence of tinnitus was the primary outcome. Baseline demographic factors and comorbidities possibly associated with tinnitus, including age, sex, and comorbidities of hearing loss, vertigo, insomnia and anxiety, were retrieved from the LHID 2000. Patients were followed until end of 2011.

RESULTS

During the study period, 780 (4.9%) hyperthyroidism patients and 2007 (3.2%) non-hyperthyroidism controls developed tinnitus. Incidence rate of tinnitus in the hyperthyroidism cohort was significantly higher in hyperthyroidism cohort (7.86 vs. 5.05 per 1000 person-years) than that in non-hyperthyroidism cohort. A higher proportion of patients with hyperthyroidism had comorbid insomnia (45.1% vs. 30.9%) and anxiety (14.0% vs. 5.73%) than those without hyperthyroidism. After adjusting for age, gender and comorbidities (vertigo, insomnia, anxiety, hearing loss), hyperthyroidism patients had 1.38-fold higher risk of tinnitus (95% CI = 1.27-1.50) than those without hyperthyroidism.

CONCLUSIONS

This large population-based study suggests patients with diagnosed hyperthyroidism was more prone to develop tinnitus. Our findings suggest evaluation for comorbid vertigo, insomnia, anxiety and/or hearing loss may identify patients who are at high risk of developing tinnitus in patients with hyperthyroidism.