亚临床甲状腺功能异常与骨质疏松

亚临床甲状腺功能异常(STD)和骨质疏松是常见的内分泌疾病,主要发生在女性和老年人群中.甲状腺激素和促甲状腺激素可直接或间接影响骨代谢,导致骨密度发生变化.而STD患者体内这两种激素水平异常,提示STD和骨质疏松之间存在一定的联系.此外,外源性甲状腺激素替代治疗亦可影响骨代谢,导致骨密度下降和骨质疏松.因此,明确STD和骨质疏松之间的联系并采取适当干预措施对于预防STD患者发生骨质疏松有重要意义.     

Subclinical thyroid dysfunction in the elderly.

Subclinical thyroid dysfunction is more common in older persons. By definition, these disorders are recognized by isolated elevation or suppression of the serum TSH concentration, in association with a normal serum free thyroxine level. Among individuals over 65 years old, subclinical hypothyroidism is found in approximately 10% of women and approximately 3% of men. It is most commonly due to autoimmune thyroiditis or previous treatment for hyperthyroidism. There may be three indications for L-thyroxine therapy: (a) presence of antithyroid antibodies, indicating substantial risk of progression to over hypothyroidism; (b) symptoms consistent with thyroid hormone deficiency; and (c) an elevated serum LDL-cholesterol. Subclinical hyperthyroidism is present in approximately 1%-2% of older persons. The most common cause is excessive thyroid hormone therapy, followed by mild endogenous hyperthyroidism due to Graves' disease or nodular goiter. These can be differentiated from other causes of low serum TSH concentration based on clinical and other laboratory and radionuclide scan criteria. The most serious consequences of subclinical hyperthyroidism are atrial fibrillation and osteoporosis, to which elderly patients are particularly predisposed.     

Subclinical thyroid dysfunction and blood pressure: a community-based study

OBJECTIVE: Overt hypothyroidism and hyperthyroidism are associated with hypertension, but it is uncertain whether the same is true of subclinical hypothyroidism and hyperthyroidism. DESIGN, SUBJECTS AND MEASUREMENTS: Cross-sectional study of 2033 participants (aged 17-89 years) in the Busselton Thyroid Study who did not have a history of thyroid disease. Systolic blood pressure (SBP), diastolic blood pressure (DBP) and the prevalence of hypertension (defined as SBP >or=140 mmHg, DBP >or=90 mmHg or on treatment for hypertension) in subjects with thyroid dysfunction and euthyroid subjects were compared using linear regression models. Subjects with treated hypertension (N = 299) were excluded from analyses of SBP and DBP but included in analyses of hypertension prevalence. RESULTS: Mean SBP, DBP and the prevalence of hypertension did not differ significantly between subjects with subclinical hypothyroidism (N = 105) and euthyroid subjects (N = 1859), nor did they differ between subjects with serum TSH concentrations in the upper reference range (2.0-4.0 mU/l; N = 418) and those with TSH concentrations in the lower reference range (0.4-2.0 mU/l; N = 1441). The prevalence of hypertension was higher in subjects with subclinical hyperthyroidism than euthyroid subjects (prevalence odds ratio 2.8, 95% confidence interval 1.3-6.0 adjusted for age, age(2) and sex), but this was based on a small number of subjects with subclinical hyperthyroidism (N = 35). CONCLUSIONS: Subclinical hypothyroidism is not associated with hypertension. The observed association between subclinical hyperthyroidism and hypertension requires confirmation in a larger sample.     

维持性血液透析患者亚临床甲状腺功能异常与心脏结构的关系

目的:探讨维持性血液透析(MHD)患者亚临床甲状腺功能异常和心脏结构的变化及其之间的关系。方法:选择MHD患者100例,透析时间3个月且病情稳定。排除临床甲状腺功能亢进或甲状腺功能减退。电化学发光仪检测甲状腺功能,包括游离三碘甲状腺原氨酸(FT3)、游离四碘甲状腺原氨酸(FT4)、促甲状腺激素(TSH),并测定同型半胱氨酸(Hcy)和C反应蛋白(CRP)。收集患者临床资料和血清生化指标。根据甲状腺功能分为亚临床甲状腺功能异常组和正常组。并应用心脏超声心动图测定患者左房内径(LAD)、左室舒张末内径(LVEDd)、左室收缩末内径(LVEDs)、左室后壁厚度(LVPWT)、室间隔厚度(IVST)、左心室质量指数(LVMI)、LVEF和相对室壁厚度(RWT)等。分析甲状腺功能和心脏结构的关系。结果:100例MHD患者中检出甲状腺功能异常者49例(49%)。甲状腺功能异常组Hcy、CRP高于正常组(P0.05),甲状腺功能异常组患者LAD,LVEDd,LVEDs,LVPWT,IVST,LVMI、RWT均高于甲状腺功能正常组(P0.05),而LVEF低于正常组(P0.01)。多因素Logistic回归分析显示FT3与左心室肥厚的发生呈负相关。结论:MHD患者常伴甲状腺功能异常,主要表现为FT3下降。FT3下降与左心室肥厚密切相关。     

Subclinical thyroid dysfunction as a risk factor for cardiovascular disease

BACKGROUND: There have been few large epidemiological studies examining the association between thyroid dysfunction and cardiovascular disease. In particular, it is uncertain if subclinical hypothyroidism is a risk factor for cardiovascular disease. METHODS: Serum thyrotropin and free thyroxine concentrations were measured in 2108 archived serum samples from a 1981 community health survey in Busselton, Western Australia (Busselton Health Study). In a cross-sectional study, we examined the prevalence of coronary heart disease in subjects with and without subclinical thyroid dysfunction. In a longitudinal study, we examined the risk of cardiovascular mortality and coronary heart disease events (fatal and nonfatal combined) to the end of 2001 (excluding subjects who had coronary heart disease at baseline). RESULTS: In the cross-sectional analysis, subjects with subclinical hypothyroidism (n = 119) had a significantly higher prevalence of coronary heart disease than euthyroid subjects (n = 1906) (age- and sex-adjusted prevalence odds ratio, 1.8; 95% confidence interval, 1.0-3.1; P = .04). In the longitudinal analysis of subjects with subclinical hypothyroidism (n = 101), there were 21 cardiovascular deaths observed compared with 9.5 expected (age- and sex-adjusted hazard ratio, 1.5; 95% confidence interval, 1.0-2.4; P = .08) and 33 coronary heart disease events observed compared with 14.7 expected (age- and sex-adjusted hazard ratio, 1.7; 95% confidence interval, 1.2-2.4; P < .01). The increased risk of coronary heart disease events remained significant after further adjustment for standard cardiovascular risk factors. Subjects with subclinical hyperthyroidism (n = 39) had no adverse outcomes. CONCLUSION: Subclinical hypothyroidism may be an independent risk factor for coronary heart disease.     

亚临床甲状腺毒症

随着高灵敏的血清促甲状腺素免疫放射测定 (ｓＴＳＨＩＲＭＡ)的应用 ,人们越来越重视引起血清促甲状腺素下降的原因 ,并提出了有关亚临床甲状腺毒症 (ｓｕｂｃｌｉｎｉｃａｌｔｈｙｒｏ ｔｏｘｉｃｏｓｉｓ)的概念。本文就这一方面研究进展作一介绍。1　血清促甲状腺素下降的原因因为Ｔ3 、Ｔ4 很小的改变就可能引起ＴＳＨ较大的变化。所以 ,ＴＳＨ检查成为最敏感的甲状腺功能检查指标。放射免疫 (ＲＩＡ)测定ＴＳＨ ,敏感度可达 0 1ｍＵ/Ｌ ,而目前广泛应用的免疫放射技术使ＴＳＨ最小检测浓度达 0 0 0 5ｍＵ/Ｌ。一般实验室的ＴＳＨ正…     

Subclinical thyroid diseases

Subclinical thyroids disease (STD) is recently defined term in clinical thyroidology, which includes mainly functional disorders. Basic diagnostic signs are: normal values of thyroid hormones (fT4, fT3) and elevated TSH level (subclinical hypothyroidism) or suppresed TSH level (subclinical hyperthyroidism). In a category of STD may be included subclinical autoimunne thyroiditis (elevated level of thyroid antigens antibodies and/or hypoechogenity in sonographic screen, increased volume of the thyroid without clinical symptoms and/or autoimminity) and microscopic lesions of papillary thyroid carcinoma. Subclinical hypothyroidism may be dangerous for tendency to development of manifest hypothyroidism and for risk of disorders of lipid profile and development of atherosclerosis and its organ complication (esp. myocardial infarction). Subclinical hyperthyroidism is a risk factor of cardiac arythmias and probably can increase a risk of cardiovascular mortality) as well for osteoporosis (esp. in peri- and post-climacteric women), and last but not least for degenerative diseases of brain (?). Indication of treatment of STD is a matter of controversies. Recomendations of experts, varied from "no therapy, monitoring only" to "treat always". Treatment of risk groups (esp. pregnant women) is probably nowadays a most rationale recommendations since results of sofisticated prospective studies will be available.     

Subclinical thyroid disease

Subclinical thyroid diseases--subclinical hyperthyroidism and subclinical hypothyroidism--are common clinical entities that encompass mild degrees of thyroid dysfunction. The clinical significance of mild thyroid overactivity and underactivity is uncertain, which has led to controversy over the appropriateness of diagnostic testing and possible treatment. In this Seminar, we discuss the definition, epidemiology, differential diagnoses, risks of progression to overt thyroid disease, potential effects on various health outcomes, and management of subclinical hyperthyroidism and subclinical hypothyroidism. Treatment recommendations are based on the degree to which thyroid-stimulating hormone concentrations have deviated from normal and underlying comorbidities. Large-scale randomised trials are urgently needed to inform how to best care for individuals with subclinical thyroid disease.     

Subclinical thyrotoxicosis and the heart.

Subclinical thyrotoxicosis is defined as a below normal thyrotropin (TSH) in association with a normal total and free thyroxine (T4) and triiodothyronine (T3). It may be caused by thyroid hormone treatment or by endogenous thyroid disease. The degree of thyrotoxicosis may be estimated by the level of TSH suppression. Subclinical thyrotoxicosis may be associated with changes in cardiac performance and morphology, but this has not been consistently found in all patient populations. Changes may include increased heart rate, increased left ventricular mass index, increased cardiac contractility, diastolic dysfunction, and the induction of ectopic atrial beats or arrhythmias. Cardiac exercise performance may be impaired. Subclinical thyrotoxicosis should be treated in patients with cardiac symptoms or disease. Treatment may include reduction of the thyroid hormone dose, treatment of the underlying thyroid condition, or beta-blockers.     

Subclinical cardiac dysfunction in sarcoidosis

Clinically apparent myocardial disease is infrequent in sarcoidosis. However, autopsy data show myocardial involvement in up to 30 percent of patients. Unexplained exertional symptomatology is a common complaint in patients with sarcoidosis. In this study, we investigated whether abnormal cardiac function might limit exercise performance in patients with sarcoidosis without overt cardiac involvement. We studied exercise responses in 35 patients with sarcoidosis and compared them with 28 untrained controls. Seventy-seven percent of the patients were symptomatic. Pulmonary function test results were lower in the group with sarcoidosis than normal controls, but they were within normal range. Only one patient had evidence of ventilatory limitation to exercise. Sixteen (46 percent) patients had abnormally increased heart rates (HRs) at rest prior to exercise testing and/or with exercise. Rapid HRs were confirmed during daily activities by continuous ambulatory electrocardiographic (ECG) monitoring. Left ventricular ejection fraction (LVEF) was measured to determine if systolic dysfunction could account for abnormal HR responses. Of patients with abnormally increased HRs, five had LVEFs less than 50 percent, and eight had normal LVEFs, of whom 75 percent had tachycardia at rest. Retrospective comparison of HR responses and LVEF between patients who did or did not receive corticosteroids revealed no significant differences between groups. We conclude that abnormal HR responses in patients without evident cardiac sarcoidosis are common and exertional symptoms in this population are often associated with chronotropic abnormalities. The exact mechanisms underlying the chronotropic abnormalities are unclear, but they likely include ventricular systolic dysfunction, sinus node dysfunction from granulomatous infiltration, or combinations of the two.     

Subclinical thyroid dysfunction and cardiac function amongst minority ethnic groups in the UK: A cross sectional study

Background

Subclinical thyroid disease is associated with abnormal cardiovascular haemodynamics and increased risk of heart failure. The burden of raised/low thyroid stimulating hormone (TSH) levels amongst South Asian (SA) and African–Caribbean (AC) minority groups in the UK is not well defined. Given that these groups are particularly susceptible to CVD, we hypothesised that STD would reflect abnormal cardiac function and heightened cardiovascular risk in these ethnic groups.

Methods

We examined SA (n = 1111, 56% male, mean age 57.6 yrs) and AC (n = 763, 44% male, mean age 59.2 yrs) participants from a large heart failure screening study. Euthyroidism is defined as TSH (0.4 – 4.9 mlU/l), subclinical hypothyroidism is defined as a raised TSH with normal serum free thyroxine (FT4) concentrations (9–19 pmol/l). Subclinical hyperthyroidism is defined as a low TSH with both FT4 and free triiodothyronine (FT3) concentrations within range (2.6–5.7 pmol/l).

Results

Across ethnic groups, prevalence of subclinical hypothyroidism was 2.9% (95% CI 2.1–3.7), and of hyperthyroidism was 2.0% (1.4–2.7). Hyperthyroidism was more common amongst SA compared to AC (2.8% vs. 0.9%, P = 0.017), while rates of subclinical hypothyroidism were similar. On multivariate analysis of variations in subclinical thyroid function, ethnicity was not independently significant.

Conclusion

The prevalence of subclinical thyroid disorders amongst SA and AC minority groups in Britain reflects levels reported in other populations. The clinical cardiovascular significance of subclinical thyroid disease is unclear, and it does not appear to be ethnically specific.     

Prognostic impact of subclinical thyroid dysfunction in heart failure

Background

Therapeutic and prognostic implications of subclinical thyroid dysfunction in patients with heart failure (HF) are unclear. We compared the prognostic impact of euthyroidism, subclinical thyroid dysfunction, and euthyroid sick syndrome (ESS) in systolic HF.

Methods

We included 1032 patients hospitalized for systolic HF (left ventricular ejection fraction [LVEF] ≤ 40%) who participated in a randomized trial assessing the effects of a HF disease management program. Patients with incomplete thyroid function tests or thyrotropic medication were excluded. In the remaining 758 subjects, the risk of all-cause death was estimated based on TSH only, or full thyroid function profile. Changes of thyroid function after six months were assessed in 451 subjects.

Results

Subclinical thyroid dysfunction was present in 103 patients at baseline (14%). No differences were found between groups regarding NYHA class (P = 0.29), and LVEF (P = 0.60). After a median follow-up of three years patients with ESS (n = 13) had a 3-fold age-adjusted increased risk of death compared to euthyroid patients (P = 0.001). However, neither subclinical hyperthyroidism (HR 1.18, 95%CI:0.82–1.70) nor hypothyroidism (HR 1.07, 95%CI:0.58–1.98) were associated with increased age-adjusted mortality risk. Subclinical thyroid dysfunction had normalized spontaneously at follow-up in 77% of patients. However, persistent subclinical thyroid dysfunction was also not associated with worse outcome.

Conclusions

In this large well-characterized HF cohort, subclinical thyroid dysfunction did not predict an increased mortality risk. Thus, in patients with moderate to severe HF, further diagnostic and therapeutic procedures for subclinical thyroid dysfunction appear dispensable. ESS was an infrequent but important indicator of a poor prognosis in HF.

Clinical trial registration

URL: http://www.controlled-trials.com. Unique identifier: ISRCTN23325295.