The association between subclinical hyperthyroidism and blood pressure in a population-based study

OBJECTIVE: Although evidence for an increased risk of hypertension in both overt hyperthyroidism and overt hypothyroidism is consistent, the relation between subclinical hyperthyroidism and blood pressure has not yet received sufficient attention. METHODS: The Study of Health in Pomerania is a population-based survey in Germany that was conducted in a previously iodine-deficient region. A study population of 4087 subjects (2050 women) without overt hyperthyroidism or increased serum thyrotropin levels was available for the present study. Serum thyrotropin levels < 0.25 mIU/l and < 0.1 mIU/l were considered decreased and suppressed, respectively. RESULTS: Multivariable analyses revealed lower adjusted mean values for systolic blood pressure in subjects with decreased [132.9 mmHg, 95% confidence interval (CI) = 131.1 mmHg; 134.8 mmHg] versus normal serum thyrotropin levels (135.0 mmHg, 95% CI = 134.4 mmHg; 135.6 mmHg, P = 0.04). The adjusted mean values for diastolic blood pressure and pulse pressure did not differ significantly between both groups. Analyses that were performed after all subjects receiving antihypertensive medications had been excluded did not reveal any statistically significant associations between decreased serum thyrotropin levels and the endpoints investigated. There was also no association of suppressed serum thyrotropin levels with blood pressure or hypertension. CONCLUSION: It is concluded that subclinical hyperthyroidism, as demonstrated by decreased as well as suppressed serum thyrotropin levels and serum free thyroid hormone levels within the reference range, is not associated with hypertension.     

The prevalence of undiagnosed thyroid disorders in a previously iodine-deficient area.

OBJECTIVE: The aim of the present study was to analyze the current status of morphologic and functional thyroid abnormalities in a previously iodine-deficient area. METHODS: The population based Study of Health in Pomerania (SHIP) comprised 4310 participants, aged 20-79 years. Thyroid function (thyrotropin [TSH] free triiodothyronine [FT(3)], and free thyroxine [FT(4)]) and serum autoantibodies to thyroperoxidase (TPOAb) were evaluated from blood samples. Thyroid structure and size were measured by ultrasound. Data from 3941 participants with no known thyroid disorders were analyzed. RESULTS: The median iodine urine excretion was 12.4 microg/dL. The rate of decreased serum TSH levels (<0.3 mIU/L) was 11.3%; 2.2% of participants had suppressed serum TSH levels (<0.1 mIU/L). The prevalence of subclinical hyperthyroidism was 1.8%, the prevalence of overt hyperthyroidism 0.4%. Elevated TSH levels were found in 1.2% of individuals. Subclinical hypothyroidism was observed in 0.5%, overt hypothyroidism in 0.7% of the sample. Elevated TPOAb were detected in 7% of subjects, 4.1% of participants had TPOAb greater than 200 IU/mL. The prevalence of goiter was 35.9%. An inhomogeneous echo pattern was detected in 35.2% and nodules in 20.2% of participants. Diffuse autoimmune thyroiditis was diagnosed in 47 subjects (1.2%). CONCLUSION: There are a number of thyroid disorders in this previously iodine-deficient region. Further studies are required to investigate the change of thyroid disorders during iodine supplementation programs.     

High occurrence of thyroid multinodularity and low occurrence of subclinical hypothyroidism among tobacco smokers in a large population study

Tobacco smoking increases the risk of goitre and Graves' disease, but the association with thyroid nodularity and hypothyroidism has not been settled. We investigated 4649 subjects from the general population with questionnaires, thyroid ultrasonography and blood tests. The results were analysed in multivariate regression models. Tobacco smoking was associated with an increased prevalence of thyroid multinodularity (odds ratio (OR) 1.9; 95% confidence interval (CI) 1.4-2.5), but not with increased prevalence of solitary thyroid nodules. The tendency was for a stronger association in the area with the most pronounced iodine deficiency (P for interaction=0.08). Lower levels of serum TSH were found among tobacco smokers (P<0.001), but this association disappeared when adjustment was made for thyroid nodularity and thyroid Volume. The prevalence of elevated TSH levels was markedly reduced among smokers (OR 0.47; 95% CI 0.33-0.67). No association was found between smoking and hyperthyroidism. The observed associations seem to be explainable by the blocking of iodine uptake and organification in the thyroid by thiocyanate, a degradation product of cyanide in tobacco smoke.     

Five‐year incidence and progression of thyroid dysfunction in an older population

Background: Very few studies have assessed both the incidence and progression of thyroid dysfunction in a single older population‐based cohort. In this study, we aimed to assess the 5‐year incidence, progression and risk factors for development of thyroid dysfunction in an older Australian population. Methods: The Blue Mountains Eye Study is a longitudinal population‐based cohort study. During 1997–1999, 1768 participants (≥55 years) had thyroid function assessed. After excluding participants reporting any form of treatment for their thyroid condition at baseline, 951 participants (91.4%) without thyroid dysfunction and 54 (5.4%) with thyroid dysfunction were re‐examined 5 years later. Thyroid dysfunction was defined using serum thyrotropin (thyroid stimulating hormone (TSH)) screen, followed by serum free T4 assessment. Results: The overall 5‐year incidence of thyroid dysfunction was 4.7% (95% confidence interval (CI) 3.4–6.1). Obesity (body mass index ≥ 30 kg/m²) and serum TSH > 2 mIU/L at baseline predicted incident overt hypothyroidism (odds ratio (OR) 4.05, CI 1.74–9.41) and (OR 5.46, CI 1.16–25.67) respectively. The 5‐year incidence of subclinical hypothyroidism was significantly higher in women than in men, 2.5% versus 0.7% (P= 0.03). Progression to overt hypothyroidism was observed in 17.9% of subjects with subclinical hypothyroidism over 5 years. Conclusions: The 5‐year incidence of thyroid dysfunction in this older population was relatively low, and was associated with obesity and serum TSH level > 2 mIU/L at baseline. Over one in six persons with subclinical hypothyroidism progressed to overt thyroid dysfunction over the 5‐year period. Our findings highlight the need for appropriate management of subclinical hypothyroidism among older people.     

Serum TSH and total T4 in the United States population and their association with participant characteristics: National Health and Nutrition Examination Survey (NHANES 1999-2002).

OBJECTIVE: Describe thyrotropin (TSH) and thyroxine (T4) levels in the U.S. population and their association with selected participant characteristics. DESIGN: Secondary analysis of data from the National Health and Nutrition Examination Survey (NHANES) collected from 4392 participants, reflecting 222 million individuals, during 1999-2002. RESULTS: Hypothyroidism prevalence (TSH > 4.5 mIU/L) in the general population was 3.7%, and hyperthyroidism prevalence (TSH < 0.1 mIU/L) was 0.5%. Among women of reproductive age (12-49 years), hypothyroidism prevalence was 3.1%. Individuals aged 80 years and older had five times greater odds for hypothyroidism compared to 12- to 49-year-olds (adjusted odds ratio [OR] = 5.0, p = 0.0002). ORs were adjusted for sex, race, annual income, pregnancy status, and usage of thyroid-related medications (levothyroxine/thyroid, estrogen, androgen, lithium, and amiodarone). Compared to non-Hispanic whites, non-Hispanic blacks had a lower risk for hypothyroidism (OR = 0.46, p = 0.04) and a higher risk for hyperthyroidism (OR = 3.18, p = 0.0005), while Mexican Americans had the same risk as non-Hispanic whites for hypothyroidism, but a higher risk for hyperthyroidism (OR = 1.98, p = 0.04). Among those taking levothyroxine or desiccated thyroid, the adjusted risk for either hypothyroidism (OR = 4.0, p = 0.0001) or hyperthyroidism (OR = 11.4, p = 4 x 10(-9)) was elevated. CONCLUSIONS: Associations with known factors such as age, race, and sex were confirmed using this data set. Understanding the prevalence of abnormal thyroid tests among reproductive-aged women informs decisions about screening in this population. The finding that individuals on thyroid hormone replacement medication often remain hypothyroid or become hyperthyroid underscores the importance of monitoring.     

Smoking and thyroid disorders--a meta-analysis

BACKGROUND: Smoking has been associated with Graves' disease, but it remains unclear if the association is present in other thyroid disorders. OUTCOME VARIABLES: Graves' disease, Graves' ophthalmopathy, toxic nodular goitre, non-toxic goitre, post-partum thyroid disease, Hashimoto's thyroiditis, or hypothyroidism. MATERIAL AND METHODS: A search of MEDLINE identified 25 studies on the association between smoking and thyroid diseases. RESULTS: In Graves' disease eight studies were available showing an odds ratio (OR) of 3.30 (95% confidence interval (CI): 2.09-5.22) in current smokers compared with never smokers. In ex-smokers there was no significant excess risk of Graves' disease (OR=1.41, 95% CI: 0.77-2.58). The OR associated with ever smoking in Graves' ophthalmopathy (4.40, 95% CI: 2.88-6.73, six studies) was significantly higher than in Graves' disease (1.90, 95% CI: 1.42-2.55, two-sided P-value <0.01). Ever smoking was not associated with toxic nodular goitre (OR=1.27, 95% CI: 0.69-2.33, three studies), while there was an increased risk of non-toxic goitre in smokers if men were excluded (OR=1.29, 95% CI: 1.01-1.65, eight studies). The risk associated with smoking was significantly lower in men than in women for both Graves' disease and non-toxic goitre. Hashimoto's thyroiditis and post-partum thyroid dysfunction were also associated with smoking while the association with hypothyroidism did not reach statistical significance. CONCLUSIONS: Cessation of smoking seems associated with a lower risk of Graves' disease than current smoking. Smoking increases the risk of Graves' ophthalmopathy beyond the risk associated with Graves' disease alone. Smoking cessation may lead to a decrease in morbidity from Graves' disease, especially in women.     

The Association between Smoking and Low Back Pain: A Meta-analysis

Objective

To assess the association between smoking and low back pain with meta-analysis.

Methods

We conducted a systematic search of the MEDLINE and EMBASE databases until February 2009. Eighty-one studies were reviewed and 40 (27 cross-sectional and 13 cohort) studies were included in the meta-analyses.

Results

In cross-sectional studies, current smoking was associated with increased prevalence of low back pain in the past month (pooled odds ratio [OR] 1.30, 95% confidence interval [CI], 1.16-1.45), low back pain in the past 12 months (OR 1.33, 95% CI, 1.26-1.41), seeking care for low back pain (OR 1.49, 95% CI, 1.38-1.60), chronic low back pain (OR 1.79, 95% CI, 1.27-2.50) and disabling low back pain (OR 2.14, 95% CI, 1.11-4.13). Former smokers had a higher prevalence of low back pain compared with never smokers, but a lower prevalence of low back pain than current smokers. In cohort studies, both former (OR 1.32, 95% CI, 0.99-1.77) and current (OR 1.31, 95% CI, 1.11-1.55) smokers had an increased incidence of low back pain compared with never smokers. The association between current smoking and the incidence of low back pain was stronger in adolescents (OR 1.82, 95% CI, 1.42-2.33) than in adults (OR 1.16, 95% CI, 1.02-1.32).

Conclusions

Our findings indicate that both current and former smokers have a higher prevalence and incidence of low back pain than never smokers, but the association is fairly modest. The association between current smoking and the incidence of low back pain is stronger in adolescents than in adults.     

Prevalence of subclinical thyroid dysfunction and its relation to socioeconomic deprivation in the elderly: a community-based cross-sectional survey

CONTEXT: Population-based screening has been advocated for subclinical thyroid dysfunction in the elderly because the disorder is perceived to be common, and health benefits may be accrued by detection and treatment. OBJECTIVE: The objective of the study was to determine the prevalence of subclinical thyroid dysfunction and unidentified overt thyroid dysfunction in an elderly population. DESIGN, SETTING, AND PARTICIPANTS: A cross-sectional survey of a community sample of participants aged 65 yr and older registered with 20 family practices in the United Kingdom. EXCLUSIONS: Exclusions included current therapy for thyroid disease, thyroid surgery, or treatment within 12 months. OUTCOME MEASURE: Tests of thyroid function (TSH concentration and free T4 concentration in all, with measurement of free T3 in those with low TSH) were conducted. EXPLANATORY VARIABLES: These included all current medical diagnoses and drug therapies, age, gender, and socioeconomic deprivation (Index of Multiple Deprivation, 2004). ANALYSIS: Standardized prevalence rates were analyzed. Logistic regression modeling was used to determine factors associated with the presence of subclinical thyroid dysfunction. RESULTS: A total of 5960 attended for screening. Using biochemical definitions, 94.2% [95% confidence interval (CI) 93.8-94.6%] were euthyroid. Unidentified overt hyper- and hypothyroidism were uncommon (0.3, 0.4%, respectively). Subclinical hyperthyroidism and hypothyroidism were identified with similar frequency (2.1%, 95% CI 1.8-2.3%; 2.9%, 95% CI 2.6-3.1%, respectively). Subclinical thyroid dysfunction was more common in females (P < 0.001) and with increasing age (P < 0.001). After allowing for comorbidities, concurrent drug therapies, age, and gender, an association between subclinical hyperthyroidism and a composite measure of socioeconomic deprivation remained. CONCLUSIONS: Undiagnosed overt thyroid dysfunction is uncommon. The prevalence of subclinical thyroid dysfunction is 5%. We have, for the first time, identified an independent association between the prevalence of subclinical thyroid dysfunction and deprivation that cannot be explained solely by the greater burden of chronic disease and/or consequent drug therapies in the deprived population.     

Hormone replacement therapy is associated with higher FEV1 in elderly women

Estrogen and progesterone use have been associated with improved pulmonary function in premenopausal women. However, little research has examined the relationship between hormone replacement therapy (HRT) and pulmonary function in postmenopausal women. We examined the relationship of HRT with spirometry in 2,353 women aged 65 yr and older participating in the Cardiovascular Health Study in 1993/1994. Current use of HRT was hypothesized to be associated with higher FEV1, higher FVC, and less pulmonary obstruction (FEV1/FVC < 65%). FEV1 was higher among current HRT users compared to noncurrent users in the following groups: overall (1.82 L versus 1.66 L, p < 0.0001), among women without asthma (1.85 L versus 1.69 L, p < 0.0001), among former smokers (1.76 L versus 1.60 L, p = 0.013), and among never smokers (1.90 L versus 1.72 L, p < 0.0001). Overall, HRT use was associated with a lower prevalence of pulmonary obstruction (OR 0.75 [95% CI 0.55, 0.99]). After controlling for potential confounders, HRT use was significantly associated with higher FEV(1) (p = 0.031) and with a lower prevalence of obstruction (OR 0.67 [95% CI 0.48, 0.95]). We conclude that postmenopausal women who use HRT have higher levels of FEV1 and less obstruction, which could not be explained by their lower rates of smoking and other health factors associated with HRT use.     

Smoking and the risk of psoriasis in women: Nurses' Health Study II

Background

Psoriasis is a common, chronic, inflammatory skin disorder. Smoking may increase the risk of psoriasis, but no prospective data are available on this relation.

Methods

We prospectively examined over a 14-year time period (1991-2005) the relation between smoking status, duration, intensity, cessation, and exposure to secondhand smoke, and incident psoriasis in 78,532 women from the Nurses Health Study II. The primary outcome was incident, self-reported, physician-diagnosed psoriasis.

Results

We documented 887 incident cases of psoriasis. Compared with those who had never smoked, the multivariate relative risk (RR) of psoriasis was 1.78 (95% confidence interval [CI], 1.46 to 2.16) for current smokers and 1.37 (95% CI, 1.17 to 1.59) for past smokers. Compared with nonsmokers, the multivariate RR of psoriasis was 1.60 (95% CI, 1.31 to 1.97) for those who had smoked 11-20 pack-years and 2.05 (95% CI, 1.66 to 2.53) for those who had smoked ≥21 pack-years. Compared with never smokers, the multivariate RR of psoriasis was 1.61 (95% CI, 1.30 to 2.00) for those who quit smoking <10 years ago, 1.31 (95% CI, 1.05 to 1.64) for 10-19 years ago, and 1.15 (95% CI, 0.88 to 1.51) for ≥20 years ago. Prenatal and childhood exposure to passive smoke was associated with an increased risk of psoriasis.

Conclusions

In this prospective analysis, current and past smoking, and cumulative measures of smoking were associated with the incidence of psoriasis. The risk of incident psoriasis among former smokers decreases nearly to that of never smokers 20 years after cessation.     

Smoking and thyroid

Current smoking in population surveys is associated with a slight dose‐dependent fall of serum TSH, likely secondary to a rise of serum FT4 and FT3 induced by activation of the sympathetic nervous system; it is independent of iodine intake. In contrast, the slightly greater thyroid size in smokers is observed in iodine‐deficient but not in iodine‐sufficient areas and caused by competitive inhibition of thyroidal iodide uptake by thiocyanate. Smokers have an increased prevalence of nontoxic goitre and thyroid multinodularity, at least in iodine‐deficient areas. Current smoking reduces dose dependently the risk of thyroid cancer, which is more pronounced for papillary than for follicular types; the risk in former smokers approaches that of never smokers. The lower TSH and lower body mass index in smokers might contribute to this reduced risk. Current smoking lowers the risk of developing thyroid peroxidase and thyroglobulin antibodies and subclinical and overt autoimmune hypothyroidism; the effect is dose dependent, but disappears within 3 years after quitting smoking. There is evidence from an animal model of experimental autoimmune thyroiditis that anti‐inflammatory effects of nicotine are involved. In contrast, smoking is a dose‐dependent risk factor for Graves’ hyperthyroidism and especially for Graves’ ophthalmopathy. Smoking is related to a higher recurrence rate of Graves’ hyperthyroidism, a higher risk on Graves’ ophthalmopathy after 131I therapy and a less favourable outcome of GO treatment with steroids or retrobulbar irradiation. The observed associations with smoking likely indicate causal relationships in view of consistent associations across studies, the presence of dose–response effects and disappearance of associations after cessation of smoking.     

Subclinical Thyroid Dysfunction and the Risk of Heart Failure Events: An Individual Participant Data Analysis From 6 Prospective Cohorts

BACKGROUND: American College of Cardiology/American Heart Association guidelines for the diagnosis and management of heart failure recommend investigating exacerbating conditions such as thyroid dysfunction, but without specifying the impact of different thyroid-stimulation hormone (TSH) levels. Limited prospective data exist on the association between subclinical thyroid dysfunction and heart failure events. METHODS AND RESULTS: We performed a pooled analysis of individual participant data using all available prospective cohorts with thyroid function tests and subsequent follow-up of heart failure events. Individual data on 25 390 participants with 216 248 person-years of follow-up were supplied from 6 prospective cohorts in the United States and Europe. Euthyroidism was defined as TSH of 0.45 to 4.49 mIU/L, subclinical hypothyroidism as TSH of 4.5 to 19.9 mIU/L, and subclinical hyperthyroidism as TSH <0.45 mIU/L, the last two with normal free thyroxine levels. Among 25 390 participants, 2068 (8.1%) had subclinical hypothyroidism and 648 (2.6%) had subclinical hyperthyroidism. In age- and sex-adjusted analyses, risks of heart failure events were increased with both higher and lower TSH levels (P for quadratic pattern <0.01); the hazard ratio was 1.01 (95% confidence interval, 0.81-1.26) for TSH of 4.5 to 6.9 mIU/L, 1.65 (95% confidence interval, 0.84-3.23) for TSH of 7.0 to 9.9 mIU/L, 1.86 (95% confidence interval, 1.27-2.72) for TSH of 10.0 to 19.9 mIU/L (P for trend <0.01) and 1.31 (95% confidence interval, 0.88-1.95) for TSH of 0.10 to 0.44 mIU/L and 1.94 (95% confidence interval, 1.01-3.72) for TSH <0.10 mIU/L (P for trend=0.047). Risks remained similar after adjustment for cardiovascular risk factors. CONCLUSION: Risks of heart failure events were increased with both higher and lower TSH levels, particularly for TSH ≥10 and <0.10 mIU/L.     

Smoking and risk of coronary heart disease among women with type 2 diabetes mellitus

BACKGROUND: Although the association between smoking and increased risk of coronary heart disease (CHD) is well established in the general population, this relationship is less well-defined among individuals with diabetes. OBJECTIVE: To assess the relationship between cigarette smoking and risk of CHD among women with type 2 diabetes mellitus in the Nurses' Health Study cohort. METHODS: The Nurses' Health Study, a prospective cohort study of 121,700 US female registered nurses surveyed in 11 states and followed up from July 1, 1976, through July 1, 1996, involved a total of 6547 women diagnosed as having type 2 diabetes mellitus. Incident cases of CHD were our main outcome measure in this study. RESULTS: We documented 458 incident cases of CHD (200 fatal CHD-related cases and 258 nonfatal myocardial infarctions) during 20 years (68,227 person-years) of follow-up. We found a dose-response relationship between current smoking status and risk of CHD among diabetic women. Compared with never smokers, the relative risks (RRs) for CHD were 1.21 (95% confidence interval [CI], 0.97-1.51) for past smokers, 1.66 (95% CI, 1.10-2.52) for current smokers of 1 to 14 cigarettes per day, and 2.68 (95% CI, 2.07-3.48) for current smokers of 15 or more cigarettes per day in multivariate analyses (P<.001 for trend). The multivariate RR of CHD among diabetic women who had stopped smoking for more than 10 years was similar to that among diabetic women who were never smokers (RR, 1.01; 95% CI, 0.73-1.38). In secondary analyses involving diabetic and nondiabetic women, the multivariate-adjusted RR of CHD for those with diabetes who currently smoked (> or = 15 cigarettes per day) compared with those who never smoked was 7.67 (95% CI, 5.88-10.01). CONCLUSIONS: Cigarette smoking is strongly associated with an increased risk of CHD among women with type 2 diabetes mellitus. Furthermore, quitting smoking seems to decrease this excess risk substantially; women with diabetes should be strongly advised against smoking.CK     

轻度碘缺乏城市食盐加碘后甲状腺疾病流行病学调查研究

 目的 评价轻度碘缺乏城市贵阳食盐加碘25年后的碘营养状态及各种甲状腺疾病的患病情况。
方法 采用分层整群抽样方法,抽取贵阳市云岩区宅吉社区20岁及以上居民1509人,测定其血清促甲状腺素（TSH）、游离T₃、游离T₄、甲状腺过氧化物酶抗体（TPOAb）、甲状腺球蛋白抗体（TgAb）水平、尿碘水平及甲状腺B超检查;同时抽取8~10岁学龄儿童80名,测定其尿碘水平。
结果 8~10岁儿童尿碘中位数为228.7 μg/L。成人临床甲状腺功能减退症（甲减）、亚临床甲减、临床甲状腺功能亢进症（甲亢）及亚临床甲亢的患病率分别为1.79%、14.12%、1.52%及1.06%,亚临床甲减的患病率显著高于临床甲减（P < 0.05）;TPOAb及TgAb的阳性率分别为14.38%及 13.59%,自身免疫性甲状腺炎的患病率为4.44%。甲状腺肿大患病率为1.06%,其中,弥漫性甲状腺肿（0.86%）较结节性甲状腺肿（0.20%）多见（P < 0.05）。
结论 食盐加碘25年后,贵阳市处于碘超足量状态,成人临床甲减、亚临床甲减、甲状腺自身抗体阳性及自身免疫性甲状腺炎的患病率均较高。     

Association between serum free thyroxine concentration and atrial fibrillation

BACKGROUND: Previous studies have suggested that minor changes in thyroid function are associated with risk of atrial fibrillation (AF). Our objective was to determine the relationship between thyroid function and presence of atrial fibrillation (AF) in older subjects. METHODS: A population-based study of 5860 subjects 65 years and older, which excluded those being treated for thyroid dysfunction and those with previous hyperthyroidism. Main outcome measures included tests of thyroid function (serum free thyroxine [T(4)] and thyrotropin [TSH]) and the presence of AF on resting electrocardiogram. RESULTS: Fourteen subjects (0.2%) had previously undiagnosed overt hyperthyroidism and 126 (2.2%), subclinical hyperthyroidism; 5519 (94.4%) were euthyroid; and 167 (2.9%) had subclinical hypothyroidism and 23 (0.4%), overt hypothyroidism. The prevalence of AF in the whole cohort was 6.6% in men and 3.1% in women (odds ratio, 2.23; P<.001). After adjusting for sex, logistic regression showed a higher prevalence of AF in those with subclinical hyperthyroidism compared with euthyroid subjects (9.5% vs 4.7%; adjusted odds ratio, 2.27; P=.01). Median serum free T(4) concentration was higher in those with AF than in those without (1.14 ng/dL; interquartile range [IQR], 1.05-1.27 ng/dL [14.7 pmol/L; IQR, 13.5-16.4 pmol/L] vs 1.10 ng/dL; IQR, 1.00-1.22 ng/dL [14.2 pmol/L; IQR, 12.9-15.7 pmol/L]; P<.001), and higher in those with AF when analysis was limited to euthyroid subjects (1.13 ng/dL; IQR, 1.05-1.26 ng/dL [14.6 pmol/L; IQR, 13.5-16.2 pmol/L] vs 1.10 ng/dL; IQR, 1.01-1.21 ng/dL [14.2 pmol/L; IQR, 13.0-15.6 pmol/L]; P=.001). Logistic regression showed serum free T(4) concentration, increasing category of age, and male sex all to be independently associated with AF. Similar independent associations were observed when analysis was confined to euthyroid subjects with normal TSH values. CONCLUSIONS: The biochemical finding of subclinical hyperthyroidism is associated with AF on resting electrocardiogram. Even in euthyroid subjects with normal serum TSH levels, serum free T(4) concentration is independently associated with AF.     

妊娠期甲状腺功能减退症的研究进展

妊娠期间由于血清甲状腺素结合球蛋白、人绒毛膜促性腺激素水平增加以及肾脏对碘的清除率增加等,致使妊娠期甲状腺激素的产生、循环、代谢和调节会随妊娠的不同阶段而改变.这为妊娠期间甲状腺疾病的诊断和治疗带来困难.因此,建立妊娠特异性血清甲状腺激素的正常参考范围非常必要,这将降低妊娠期甲状腺疾病的漏诊率和误诊率.妊娠期母体甲状腺功能不足包括临床甲状腺功能减退症(甲减)、亚临床甲减和低甲状腺素血症,可以对后代的神经智力发育造成损伤.妊娠期甲减妇女应该接受左甲状腺素(L-T4)替代治疗,治疗目标为血清促甲状腺激素(TSH)水平在妊娠早期不超过2.5 mIU/L;妊娠中期和妊娠晚期不超过3.0 mIU/L或者不超过妊娠期特异性血清TSH的正常参考范围.     

Evaluation of thyroid functions with respect to iodine status and TRH test in chronic autoimmune thyroiditis

Objective: Chronic autoimmune thyroiditis (CAT) is the most common form of thyroiditis in childhood and a frequent cause of acquired hypothyroidism. The objective of this study was to evaluate the thyroid status of childrenand adolescents with CAT with respect to iodine status and diagnostic values of thyrotropin-releasing hormone (TRH) test. Methods: Seventy-one children (mean age: 11.6 years) were studied in a retrospective analysis. Free thyroxine (T4), thyrotropin (TSH), TSH response to TRH test, thyroid autoantibodies, thyroid sonography, and urinary iodine excretion (UIE) were evaluated. Results: At diagnosis, 8.5% of patients had overt hypothyroidisim and 36.6% subclinical hypothyroidism; 5.6% had overt hyperthyroidisim and 8.5% had subclinical hyperthyroidism. Of them, 40.8% were euthyroid. Median UIE was 51 mg/L in overt hypothyroidism and 84 mg/L in subclinical hypothyroidism. The values were 316 mg/L and 221 mg/L in overt and subclinical hyperthyroidism, respectively. Basal TSH showed a strong correlation with peak TSH level on TRH test. Thirty-four percent of patients with normal basal TSH level showed an exaggerated TSH response. Conclusion: Iodine deficiency was seen more in cases with hypothyroidism, while excess of iodine was observed to be more frequent in hyperthyroid patients. Iodine status was a strong predictorof the thyroid status in CAT. TRH test may be helpful in further delineating patients with subclinical hypothyroidism. Conflict of interest:None declared.     

Thyroid dysfunction and autoimmunity in infertile women.

A prospective study was undertaken in 438 women (ages, 32 +/- 5 years) with various causes of infertility, and in 100 age-matched (33 +/- 5 years) healthy parous controls with the aim of assessing the prevalence of autoimmune thyroid disease (AITD) and hitherto undisclosed alterations of thyroid function. Female origin of the infertility was diagnosed in 45% of the couples, with specific causes including endometriosis (11%), tubal disease (30%), and ovarian dysfunction (59%). Male infertility represented 38% and idiopathic infertility 17% of the couples. Overall, median thyrotropin (TSH) was significantly higher in patients with infertility compared to controls: 1.3 (0.9) versus 1.1 (0.8) mIU/L. Serum TSH above normal (>4.2 mIU/L) or suppressed TSH (<0.27 mIU/L) levels were not more prevalent in the infertile women than in controls. The prevalence of positive thyroid peroxidase antibody (TPO-Ab) was higher in all investigated women of infertile couples, compared to controls (14% vs. 8%), but the difference was not significant. However, in infertility of female origin, a significant higher prevalence of positive TPO-Ab was present, compared to controls: 18% versus 8%. Furthermore, among the female causes, the highest prevalence of positive antibodies was observed in women with endometriosis (29%). When thyroid antibodies were positive, both hypothyroidism and hyperthyroidism were more frequent in all women of infertile couples and in the women with a female infertility cause, compared to women in the same groups but without positive TPO-Ab. The present study shows that in infertile women, thyroid autoimmunity features are significantly more frequent than in healthy fertile controls and this was especially the case for the endometriosis subgroup.     

Dose-dependent effect of smoking on risk of coronary heart disease,heart failure and stroke in individuals with type 1 diabetes

Aims/hypothesis

The aim of this study was to assess the potential dose-dependent effects of smoking on the risk of CHD, heart failure and stroke in individuals with type 1 diabetes.

Methods

The study included 4506 individuals with type 1 diabetes who were participating in the Finnish Diabetic Nephropathy (FinnDiane) study. Intensity of smoking was estimated by packs per day and cumulative smoking by pack-years. Cox regression analyses were used to estimate the risk of incident CHD, heart failure or stroke during follow-up.

Results

One pack per day significantly increased the risk of incident CHD in current smokers compared with never smokers (HR 1.45 [95% CI 1.15, 1.84]), after adjustment for age, sex, HbA_1c, hypertension, duration of diabetes and BMI. The risk of CHD in former smokers was similar to the risk in never smokers. The risk of incident heart failure was 1.43 (95% CI 1.03, 1.97) in current smokers per one pack per day and 1.37 (95% CI 1.05, 1.77) in former smokers, while the risk of incident stroke was 1.70 (95% CI 1.26, 2.29) and 1.49 (95% CI 1.14, 1.93), respectively. After further adjustments for lipids, however, the difference in the risk of heart failure in current and former smokers was no longer significant. Cumulative smoking data were similar to smoking intensity data.

Conclusions/interpretation

There is a dose-dependent association between smoking and cardiovascular disease in individuals with type 1 diabetes. In men in particular, the risk of incident stroke remains high even after smoking cessation and is increased in current and former smokers independently of other risk factors.