亚临床甲状腺功能异常与心血管疾病的关系

临床研究显示,亚临床甲状腺功能异常与心血管疾病之间存在密切的关系.亚临床甲状腺功能减退通常伴有血脂异常、高凝状态、纤维蛋白溶解活性减低等心血管疾病危险因素,其与动脉粥样硬化、冠心病和心血管死亡的风险显著相关.另一方面,亚临床甲状腺功能亢进与心房颤动发生风险显著相关,但与心血管死亡风险的相关性尚不清楚.对于亚临床甲状腺功能异常进行治疗是否能够带来心血管获益,目前尚无确切结论.     

亚临床甲状腺功能异常与心血管疾病的关系

临床研究显示,亚临床甲状腺功能异常与心血管疾病之间存在密切的关系.亚临床甲状腺功能减退通常伴有血脂异常、高凝状态、纤维蛋白溶解活性减低等心血管疾病危险因素,其与动脉粥样硬化、冠心病和心血管死亡的风险显著相关.另一方面,亚临床甲状腺功能亢进与心房颤动发生风险显著相关,但与心血管死亡风险的相关性尚不清楚.对于亚临床甲状腺功能异常进行治疗是否能够带来心血管获益,目前尚无确切结论.     

亚临床甲状腺功能异常与心血管疾病的关系

临床研究显示,亚临床甲状腺功能异常与心血管疾病之间存在密切的关系.亚临床甲状腺功能减退通常伴有血脂异常、高凝状态、纤维蛋白溶解活性减低等心血管疾病危险因素,其与动脉粥样硬化、冠心病和心血管死亡的风险显著相关.另一方面,亚临床甲状腺功能亢进与心房颤动发生风险显著相关,但与心血管死亡风险的相关性尚不清楚.对于亚临床甲状腺功能异常进行治疗是否能够带来心血管获益,目前尚无确切结论.     

江苏社区人群亚临床甲状腺功能异常和血压关系的研究

通过对6044名江苏社区人群横断面流行病学调查发现,亚临床甲状腺功能异常(亚临床甲状腺功能亢进症/亚临床甲状腺功能减退症)与血压的升高无明显相关性.     

亚临床甲状腺疾病

亚临床甲状腺疾病是指无或有轻微甲状腺疾病相关症状、仅在实验室检查中或通过影像学手段发现的甲状腺异常，包括甲状腺意外结节、亚临床甲状腺功能亢进、轻微甲状腺功能减退先进。它们可影响正常的生理及代谢过程，部分患者可出现相关临床症状。亚临床甲状腺疾病应视患者的具体情况进行个体化处置。     

江苏社区人群亚临床甲状腺功能异常和血压关系的研究

通过对6044名江苏社区人群横断面流行病学调查发现,亚临床甲状腺功能异常(亚临床甲状腺功能亢进症/亚临床甲状腺功能减退症)与血压的升高无明显相关性.     

江苏社区人群亚临床甲状腺功能异常和血压关系的研究

通过对6044名江苏社区人群横断面流行病学调查发现,亚临床甲状腺功能异常(亚临床甲状腺功能亢进症/亚临床甲状腺功能减退症)与血压的升高无明显相关性.     

江苏社区人群亚临床甲状腺功能异常和血压关系的研究

通过对6044名江苏社区人群横断面流行病学调查发现,亚临床甲状腺功能异常(亚临床甲状腺功能亢进症/亚临床甲状腺功能减退症)与血压的升高无明显相关性.     

江苏社区人群亚临床甲状腺功能异常和血压关系的研究

通过对6044名江苏社区人群横断面流行病学调查发现,亚临床甲状腺功能异常(亚临床甲状腺功能亢进症/亚临床甲状腺功能减退症)与血压的升高无明显相关性.     

江苏社区人群亚临床甲状腺功能异常和血压关系的研究

通过对6044名江苏社区人群横断面流行病学调查发现,亚临床甲状腺功能异常(亚临床甲状腺功能亢进症/亚临床甲状腺功能减退症)与血压的升高无明显相关性.     

Subclinical thyroid dysfunction and cardiovascular consequences: An alarming wake-up call?

Subclinical thyroid dysfunction (STD), presenting as subclinical hypothyroidism (SHypo) or subclinical hyperthyroidism (SHyper), defined as abnormal serum thyrotropin (TSH) and normal free thyroid hormones, is associated with increased cardiovascular (CV) risk and mortality. Depending on the degree of such dysfunction, atherosclerosis, coronary artery disease, heart failure and cardiac arrhythmias, predominantly atrial fibrillation, characterize both disorders and increase CV and total mortality compared to euthyroid persons. There are some differences in the mechanisms involved in the increased CV risk incurred by each type of STD, with more traditional CV risk factors clustered in SHypo than in SHyper, while the role of the TSH or its absence thereof, together with the respective, even subtle, changes incurred in thyroid hormone concentrations, seem to adversely influence the CV system in both types of STD. There is evidence that treatment of STD confers potential benefits by reducing CV events, however, no consensus has been reached due to lack of randomized controlled studies. Nevertheless, due to accumulating evidence from observational studies, many authorities agree that individuals with severe SHypo (TSH > 10 mIU/L) or grade 2 SHyper (TSH < 0.1 mIU/L) should receive treatment, mostly for the increased risk of CV morbidity and mortality. The evidence reviewed herein should alert and help the clinician to wake up to these two potentially alarming conditions of STD as they may confer serious CV complications, while their treatment appears quite beneficial.     

Subclinical thyroid disorders: the menace of the Trojan horse

This review aims at summarizing some new data regarding the so-called subclinical thyroid disease and incorporate the knowledge in order to provide a basis for a more careful approach to these morbidities. SHyper represents a considerable risk factor for atrial fibrillation in the elderly and also for osteoporosis, which is a major cause of morbidity in postmenopausal women. SHypo is not an innocuous condition. It progresses to thyroid failure in patients with positive thyroid antibodies, it affects neurobehavior, it may influence cardiac contractility at exercise and it is associated with an impaired lipid profile that may provoke atherosclerosis. Therefore, both conditions should be screened more carefully in the community and treatment should be more often considered.     

Blood coagulation, fibrinolytic activity and lipid profile in subclinical thyroid disease: subclinical hyperthyroidism increases plasma factor X activity

BACKGROUND AND OBJECTIVES: Various abnormalities of coagulation and fibrinolysis occur in patients with thyroid diseases, and may range from subclinical laboratory abnormalities to clinically significant disorders of coagulation and, rarely, major haemorrhage or thromboembolism. The influence of subclinical hypothyroidism (SHypo) on haemostasis is controversial, both hypercoagulable and hypocoagulable states have been reported. A hypercoagulable state might be a risk factor for thromboembolic disease in SHypo. On the other hand, subclinical hyperthyroidism (SCHyper) is associated with enhanced cardiovascular risk. In the English literature, there are no studies on changes in coagulation and fibriolytic status in subjects with SCHyper. Therefore, the aim of the present study was to investigate the markers of endogenous coagulation and fibrinolysis, and to evaluate the relationships between serum lipid profile and thyroid hormones and these haemostatic parameters in subclinical thyroid patients. DESIGN AND METHODS: Various haemostatic parameters were investigated in 30 patients with SHypo and 20 patients with SCHyper and compared to 20 euthyroid controls. Prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen, factors V, VII, VIII, IX and X activities, vWF, antithrombin III (AT III), protein C, protein S, tissue plasminogen activator (t-PA) and tissue plasminogen activator inhibitor-1 (PAI-1), as well as common lipid variables, were measured. The relationships between serum thyroid hormones and these haemostatic parameters were examined. RESULTS: Compared with the control subjects, only FX activity was significantly increased in patients with SCHyper (P < 0.01). Total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) levels were significantly higher in patients with SHypo compared with the control group (P < 0.001 and P < 0.01, respectively). TC levels were significantly higher in patients with SCHyper than in controls (P < 0.05). No differences could be found in coagulation/fibrinolysis parameters between subclinical hypothyroid patients and control subjects. In patients with SCHyper, serum TSH level was positively correlated with FX activity (r: 0.58, P < 0.01) and inversely correlated with PAI-1 (r: -0.55. P < 0.05). Serum TG levels were inversely correlated with plasma activities of factors V, VII, VIII, IX, X and vWF (r: -0.83, P < 0.001; r: -0.68, P < 0.05; r: -0.61, P < 0.05; r: -0.77, P < 0.01; r: -0.63, P < 0.05; r: -0.60, P < 0.05, respectively). Serum TC levels were positively correlated with plasma fibrinogen levels (r: 0.72, P < 0.05). Serum HDL-C levels were positively correlated with protein S activity (r: 0.68, P < 0.05) and negatively correlated with F VII activity (r: -0.69, P < 0.05). Also, in patients with SHypo, serum TG levels were positively correlated with serum TSH levels (r: 0.42, P < 0.05), plasma activities of factors V, VII and X (r: 0.42, P < 0.05; r: 0.54, P < 0.01; r: 0.57, P < 0.01, respectively) and negatively correlated with plasma fibrinogen levels (r: -0.41, P < 0.05). Serum TC levels were positively correlated with factors V and X (r: 0.42, P < 0.05; r: 0.58, P < 0.01, respectively) and negatively correlated with t-PA Ag levels (r: -0.44, P < 0.05). Serum HDL-C levels were inversely correlated with F VII activity (r: -0.48, P < 0.05). INTERPRETATION AND CONCLUSIONS: Some differences were found in the haemostatic parameters and lipid profile between the subclinical thyroid patients and healthy controls. Increased factor X activity in patients with subclinical hyperthyroidism represent a potential hypercoagulable state, which might augment the already existing risk for atheroscleroic complications. Also, subclinical hypothyroid patients exhibit a more atherogenic lipid profile compared with healthy individuals. Therefore, subclinical hypothyroidism is also associated with an increased risk of cardiovascular disease. However, thyroid hormones may play a role at different levels of the complex haemostatic system in subclinical thyroid disease.     

Mortality rate of chronically ill geriatric patients with subnormal serum thyrotropin concentration: a 2-yr follow-up study

We investigated the natural course of subclinical thyroid dysfunctions in geriatric patients, especially regarding their association with mortality rate. Ninety-three randomly selected chronically ill geriatric patients 64–87 (median: 77) yr of age participated in the screening study with a 2-yr follow-up. Serum thyrotropin (thyroid-stimulating hormone [TSH]), free thyroxine, triiodothyronine, and antibodies against thyroid peroxidase were measured. During the follow-up, patients with suppressed TSH levels who were otherwise euthyroid (untreated) had a higher mortality rate than patients with normal TSH (5/8 vs 18/64; p<0.05). The initial clinical state of these two subgroups did not differ significantly. Two-thirds of patients with treated hyperthyroidism died. The mortality rate of patients with initially subnormal but not suppressed TSH level was average and did not differ statistically from either the euthyroid or the hyperthyroid groups. Only 1 of 13 euthyroid patients with positive thyroid antibody titers developed a subsequent subclinical hypothyroidism. Subclinical hyperthyroidism was found to be associated with a higher mortality rate in chronically ill geriatric patients, which justifies screening for thyroid dysfunction and treatment of subclinical hyperthyroidism. In addition, a subnormal but measurable TSH was not indicative regarding the future development of hyperthyroidism. Finally, during the 2-yr follow-up, antibody positivity in the euthyroid cases did not prove to be predictive for the subsequent development of hypothyroidism.     

Assessment of anxiety in subclinical thyroid disorders

It is well known that manifest thyroid dysfunction causes mood disorders. In the literature there are few studies related with subclinical thyroid dysfunction and anxiety. We aimed to determine if there exists a relation between the anxiety and subclinical thyroid dysfunction. This study was carried out in the Meram Medical Faculty of Sel?uk University, Department of Endocrinology and Metabolism. Eighty-five outpatients were enrolled into the study. In the presence of normal fT(3) and fT(4), patients were grouped as subclinical hyperthyroid with TSH lower than 0.1 mU/L (n = 24), subclinical hypothyroid with TSH higher than 4.5 mU/L (n = 32) and euthyroid subjects (n = 29). Beck's Anxiety Inventory (BAI) was administered to all patients. There was no any statistically significant difference between euthyroid and study groups in terms of age, gender, weight and height (p<0.05). One-way ANOVA showed that both of the subclinical hypothyroid and subclinical hyperthyroid groups had significantly higher anxiety scores than euthyroid group (F: 11.4, p<0.001). Manifest hypothyroidism and hyperthyroidism, as causes of mental and neurological dysfunction have been known for a long time, but the relation between subclinical thyroid dysfunction and anxiety is less well studied. We have found that subclinical thyroid dysfunction increases the anxiety of patients whether hyperthyroid or hypothyroid. Overlap of symptoms common to both thyroid dysfunction and anxiety is an important limitation in this study. Mood changes especially anxiety due to subclinical thyroid dysfunction may have an important impact on the patient's quality of life. Negative effect on quality of life may be an indication of treatment in these patients. It is the first study evaluating anxiety in subclinical hypothyroidism in the literature.     

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.     

Thyroid Function Abnormalities and Cognitive Impairment in Elderly People: Results of the Invecchiare in Chianti Study

OBJECTIVES: To investigate thyroid function testing abnormalities in older persons and to explore the relationship between thyroid dysfunction and cognition.
DESIGN: Cross-sectional.
SETTING: Community-based.
PARTICIPANTS: One thousand one hundred seventy-one men and women aged 23 to 102.
MEASUREMENTS: Thyroid function was evaluated by measuring plasma concentrations of thyrotropin (TSH), free thyroxine (FT4), and free triiodothyronine (FT3). Cognition was evaluated using the Mini-Mental State Examination (MMSE). Prevalence of overt and subclinical thyroid dysfunction was evaluated in different age groups (<65 vs ≥65). Age trends in TSH, FT4, and FT3 were examined in euthyroid participants. The cross-sectional association between thyroid dysfunction and MMSE score was evaluated adjusting for confounders.
RESULTS: Subclinical hypothyroidism and subclinical hyperthyroidism were more prevalent in older than in younger participants (subclinical hypothyroidism, 3.5% vs 0.4%, P <.03; subclinical hyperthyroidism, 7.8% vs 1.9%, P <.002). In euthyroid participants, TSH and FT3 declined with age, whereas FT4 increased. Older participants with subclinical hyperthyroidism had lower MMSE scores than euthyroid subjects (22.61±6.88 vs 24.72±4.52, P <.03). In adjusted analyses, participants with subclinical hyperthyroidism were significantly more likely to have cognitive dysfunction (hazard rate=2.26, P =.003).
CONCLUSION: Subtle age-related changes in FT3, FT4, and TSH occur in individuals who remain euthyroid. Subclinical hyperthyroidism is the most prevalent thyroid dysfunction in Italian older persons and is associated with cognitive impairment.     

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.     

Coronary flow reserve is impaired in subclinical hypothyroidism

OBJECTIVE: Although the cardiovascular system is highly sensitive to thyroid hormones, the cardiovascular effects of subtle thyroid dysfunction such as subclinical hypothyroidism (SHT) remain unclear. Therefore, we investigated coronary flow reserve (CFR) reflecting coronary microvascular function in patients with SHT. METHODS: Fifty subjects with SHT and 30 control subjects with normal serum thyroid hormones and TSH levels were included in this study. Coronary diastolic peak flow velocities were measured at baseline and after dipyridamole infusion. CFR was calculated as the ratio of hyperemic to baseline diastolic peak velocity. RESULTS: Age, gender, diastolic and systolic blood pressure, body mass index (BMI), serum lipid parameters, and thyroid hormone levels were similar between the groups. Heart rate was significantly lower in the SHT group. Left ventricular diastolic filling parameters were significantly different in the SHT group while other echocardiographic parameters were similar. CFR values were significantly lower in subjects with SHT than in the control group (2.38 +/- 0.44 vs. 2.98 +/- 0.47, p < 0.0001). CONCLUSIONS: These findings suggest that CFR, which reflects coronary microvascular function, is impaired in patients with SHT.     

Long-term follow-up of thyroid function in patients who received bone marrow transplantation during childhood and adolescence

An increasing number of long-term surviving bone marrow transplant (BMT) recipients have recovered from their primary disease but are at risk of developing failure of endocrine organs. We investigated 147 patients who underwent allogeneic BMT. Thyroid function was evaluated by serial measurement of basal TSH and free T4 levels as well as by TRH provocative test. Thyroid ultrasound examination was performed for evaluation of thyroid tumor after BMT. Five patients were found to have overt thyroid dysfunction (hypothyroidism in four patients and hyperthyroidism in one patient). Twenty-three patients in the under 9-yr-old group at BMT and 16 patients in the over 10-yr-old group at BMT had subclinical compensated hypothyroidism. Younger age at BMT was the strongest factor for developing thyroid dysfunction, compared with older age (P < 0.001). Only in patients with subclinical compensated hypothyroidism did median basal and peak TSH increase to the upper half of the normal range by 8 yr after BMT and then returned slightly to the middle of the normal range spontaneously. These results suggest that thyroid dysfunction in long-term BMT survivors depends on age at BMT, with a greater risk among younger patients, indicating the need for life-long surveillance.