Prevalence Of Subclinical Thyroid Disease Research Articles

Changes in thyroid function and evolution of subclinical thyroid disease in older men.

Prevalence of subclinical thyroid disease increases with age, but optimal detection and surveillance strategies remain unclear particularly for older men. We aimed to assess thyroid stimulating hormone (TSH) and free thyroxine (FT4) concentrations and their longitudinal changes, to determine the prevalence and incidence of subclinical thyroid dysfunction in older men. Longitudinal study of 994 community-dwelling men aged ≥70 years without known or current thyroid disease, with TSH and FT4 concentrations assessed at baseline and follow-up (after 8.7 ± 0.9 years). Factors associated with incident subclinical thyroid dysfunction were examined by logistic regression and receiver operating characteristic analyses. At baseline, 85 men (8.6%) had subclinical hypothyroidism and 10 (1.0%) subclinical hyperthyroidism. Among 899 men euthyroid at baseline (mean age 75.0 ± 3.0 years), 713 (79.3%) remained euthyroid, 180 (20.0%) developed subclinical/overt hypothyroidism, and 6 (0.7%) subclinical/overt hyperthyroidism. Change in TSH correlated with baseline TSH (r = .16, p < .05). Change in FT4 correlated inversely with baseline FT4 (r = -0.35, p < .05). Only higher age and baseline TSH predicted progression from euthyroid to subclinical/overt hypothyroidism (fully-adjusted odds ratio [OR] per year=1.09, 95% confidence interval [CI] = 1.02-1.17, p = .006; per 2.7-fold increase in TSH OR = 65.4, CI = 31.9-134, p < .001). Baseline TSH concentration ≥2.34 mIU/L had 76% sensitivity and 77% specificity for predicting development of subclinical/overt hypothyroidism. In older men TSH concentration increased over time, while FT4 concentration showed little change. Subclinical or overt hypothyroidism evolved in one fifth of initially euthyroid men, age and higher baseline TSH predicted this outcome. Increased surveillance for thyroid dysfunction may be justified in older men, especially those with high-normal TSH.

The prevalence of subclinical thyroid disease in a sample of pregnant women with hypertension during labor: A cross-sectional study

Background and objective: Hypertensive disorders during pregnancy remain one of the major causes of maternal and fetal morbidity and death. Subclinical thyroid disease may play an important underlying cause of hypertension during pregnancy. This study aimed to find out the prevalence of subclinical thyroid disease in a sample of pregnant women with hypertension during labor. Methods: A cross sectional study was performed at the Maternity Teaching Hospital, Erbil city, Kurdistan region, Iraq, from January to December 2016.Two hundred fifty women were included in this study, all with hypertension related to pregnancy (pregnancy induced hypertension, pre-eclampsia, and eclampsia). The TSH and serum free T4 levels were estimated and the participants were classified to be euthyroid, subclinical hyperthyroid, or subclinical hypothyroid. A specially designed questionnaire was used to collect data. Results: Of the 250 women included in our study, 191 (76.4%) had TSH levels within the normal range and were considered to be euthyroid, 59 (23.4%) had TSH levels more than 4 milliunits/L meeting the criteria of sub-clinical hypothyroidism. There were no cases of subclinical hyperthyroidism (TSH level below normal). Conclusion: Subclinical thyroid disease may be a contributory factor in the development of hypertension during pregnancy. No correlation was found between subclinical hyperthyroidism and hypertension during pregnancy.

Quantitative bias analysis of the association between subclinical thyroid disease and two perfluoroalkyl substances in a single study

Exposure to perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) has been associated with the occurrence of thyroid disease in some epidemiologic studies. We hypothesized that in a specific epidemiologic study based on the National Health and Nutrition Examination Survey, the association of subclinical thyroid disease with serum concentration of PFOA and PFOS was due to reverse causality. Thyroid hormone affects glomerular filtration, which in turn affects excretion of PFOA and PFOS. We evaluated this by linking a model of thyroid disease status over the lifetime to physiologically based pharmacokinetic models of PFOA and PFOS. Using Monte Carlo methods, we simulated the target study population and analyzed the data using multivariable logistic regression. The target and simulated populations were similar with respect to age, estimated glomerular filtration rate, serum concentrations of PFOA and PFOS, and prevalence of subclinical thyroid disease. Our findings suggest that in the target study the associations with subclinical hypothyroidism were overstated and the results for subclinical hyperthyroidism were, in general, understated. For example, for subclinical hypothyroidism in men, the reported odds ratio per ln(PFOS) increase was 1.98 (95% CI 1.19–3.28), whereas in the simulated data the bias due to reverse causality gave an odds ratio of 1.19 (1.16–1.23). Our results provide evidence of bias due to reverse causality in a specific cross-sectional study of subclinical thyroid disease with exposure to PFOA and PFOS among adults.

Thyroid function and internal carotid artery stenosis in ischemic stroke

Thyroid dysfunction has been known to be closely associated with increased vascular events. The aims of the present study included determining the prevalence of subclinical thyroid disease and relationships between normal ranges of thyroid function and internal carotid artery steno-occlusion (ICS) in patients with ischemic stroke. From March 2007 to February 2008, 382 consecutive patients with ischemic stroke referred to the neurovascular ultrasound laboratory were analyzed. ICS was defined as greater than 50% luminal narrowing or complete obstruction in at least 1 internal carotid artery. Subclinical thyroid disease was determined by free thyroxine (fT4) and thyroid stimulating hormone (TSH) measurements. After the exclusion of patients with abnormal levels of thyroid hormones, normal ranges of fT4 were classified into 3 groups: low-normal (fT4, 11.0~12.3 pmol/L), mid-normal (12.4~15.4), and high-normal (15.5~24.0) thyroid groups. There were 17 patients (4.5%) with subclinical hypothyroidism and 6 (1.6%) with subclinical hyperthyroidism. There were 301 patients (78.8%) with normal fT4 and TSH levels, and among them, 67 patients (22.3%) had ICS. There was a significantly higher percentage of ICS in the low-normal thyroid group than in the other groups. By multivariate regression analysis, the low-normal fT4 group had an OR of 2.80 (95% confidence interval, 1.39-5.66) for ICS compared to the mid-normal group. In patients with ischemic stroke, the prevalence of subclinical thyroid disease was similar to the general population, and in euthyroid patients, low-normal thyroid function was independently associated with a higher percentage of ICS.

Subclinical thyroid dysfunctions are independent risk factors for mortality in a 7.5-year follow-up: the Japanese–Brazilian thyroid study

The currently available data concerning the influence of subclinical thyroid disease (STD) on morbidity and mortality are conflicting. Our objective was to investigate the relationships between STD and cardiometabolic profile and cardiovascular disease at baseline, as well as with all-cause and cardiovascular mortality in a 7.5-year follow-up. Prospective, observational study. An overall of 1110 Japanese-Brazilians aged above 30 years, free of thyroid disease, and not taking thyroid medication at baseline were studied. In a cross-sectional analysis, we investigated the prevalence of STD and its relationship with cardiometabolic profile and cardiovascular disease. All-cause and cardiovascular mortality rates were assessed for participants followed for up to 7.5 years. Association between STD and mortality was drawn using multivariate analysis, adjusting for potential confounders. A total of 913 (82.3%) participants had euthyroidism, 99 (8.7%) had subclinical hypothyroidism, and 69 (6.2%) had subclinical hyperthyroidism. At baseline, no association was found between STD and cardiometabolic profile or cardiovascular disease. Multivariate-adjusted hazard ratios (HRs (95% confidence interval)) for all-cause mortality were significantly higher for individuals with both subclinical hyperthyroidism (HR, 3.0 (1.5-5.9); n=14) and subclinical hypothyroidism (HR, 2.3 (1.2-4.4); n=13) than for euthyroid subjects. Cardiovascular mortality was significantly associated with subclinical hyperthyroidism (HR, 3.3 (1.4-7.5); n=8), but not with subclinical hypothyroidism (HR, 1.6 (0.6-4.2); n=5). In the Japanese-Brazilian population, subclinical hyperthyroidism is an independent risk factor for all-cause and cardiovascular mortality, while subclinical hypothyroidism is associated with all-cause mortality.

Standardisation of rates using logistic regression: a comparison with the direct method

BackgroundStandardisation of rates in health services research is generally undertaken using the direct and indirect arithmetic methods. These methods can produce unreliable estimates when the calculations are based on small numbers. Regression based methods are available but are rarely applied in practice. This study demonstrates the advantages of using logistic regression to obtain smoothed standardised estimates of the prevalence of rare disease in the presence of covariates.MethodsStep by step worked examples of the logistic and direct methods are presented utilising data from BETS, an observational study designed to estimate the prevalence of subclinical thyroid disease in the elderly. Rates calculated by the direct method were standardised by sex and age categories, whereas rates by the logistic method were standardised by sex and age as a continuous variable.ResultsThe two methods produce estimates of similar magnitude when standardising by age and sex. The standard errors produced by the logistic method were lower than the conventional direct method.ConclusionRegression based standardisation is a practical alternative to the direct method. It produces more reliable estimates than the direct or indirect method when the calculations are based on small numbers. It has greater flexibility in factor selection and allows standardisation by both continuous and categorical variables. It therefore allows standardisation to be performed in situations where the direct method would give unreliable results.

Should we treat all subjects with subclinical thyroid disease the same way?

Overt hypothyroidism and hyperthyroidism are associated with an increased cardiovascular risk (1). Despite the high prevalence of subclinical thyroid disease and the potential progression to overt disease, the risk associated with this condition is debated (2, 3). The potential cardiovascular risk in subclinical thyroid disease is an important factor that can affect decisions about the screening and treatment of patients (4, 5). Alterations of cardiovascular function have been reported in young and middle-aged individuals with persistent subclinical hyperthyroidism (SHyper) (4, 5). Moreover, the atherosclerotic risk was found to be higher in SHyper patients with decreased serum thyrotrophin (TSH) levels (6). In elderly individuals, SHyper is associated with an increased prevalence of atrial fibrillation, and the hypercoagulable state could predispose these subjects to an increased thromboembolic risk (7). SHyper has been linked to several important independent cardiovascular risk factors, and if left untreated could, in the long term, increase morbidity andmortality due to coronary heart disease, stroke, heart failure, and sudden death, especially in the elderly. Three studies have assessed cardiovascular mortality in patients with endogenous SHyper (7–9). No adverse outcome and no increased cardiovascular mortality was observed by Cappola et al. (7) and Walsh et al. (9) in patients with endogenous SHyper as a whole, or in the subgroup with serum TSH less than 0.1 mIU/l and serum TSH between 0.1 and 0.4 mIU/l. On the contrary, in another study, survival was poorest in subjects with low serum TSH (!0.5 mIU/l) (8), and there was no difference in survival between patients with a low but detectable TSH and undetectable serum TSH. The increased mortality was due to cardiovascular diseases. Interestingly, thyroid hormone use was not related to cardiovascular mortality among women with baseline TSH below the normal range in the community dwelling study by Bauer et al. (10). The epidemiological studies of endogenous SHyper have several limitations, subclinical thyroid dysfunction may not be stable over time and not all studies provided information about: 1) the pre-diagnosis duration of SHyper; 2) the diagnosis of SHyper; and3) the progression or treatment of thyroid dysfunction of the members of some cohorts. Lastly, the analysiswas not always adjusted for associated cardiovascular risk factors.

Enfermedad tiroidea subclínica en la población anciana sana institucionalizada

Our aim was to determine the prevalence of subclinical thyroid disease in a healthy institutionalised geriatric population. We determined TSH, free T4 and antithyroid antibodies from 242 healthy elderly subjects living in Andalusian public nursing homes. Subclinical hypothyroidism was detected in 3.71% of cases; clinical hypothyroidism in 1.65%; subclinical hyperthyroidism in 0.82%,and autoimmune disease in 10.33%. There is a high rate of clinically undetected thyroid dysfunction among the healthy institutionalised geriatric population. Therefore, a hormonal screening may be justified in this population.