DECREASED HDL CHOLESTEROL IN SUBCLINICAL HYPOTHYROIDISM: THE EFFECT OF L‐THYROXINE THERAPY
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SUMMARY Thyroid function and lipid tests were measured in 29 premenopausal women with subclinical hypothyroidism. This group was compared with 41 euthyroid women matched for age and metabolic parameters. In basal condition there was no difference in thyroid hormone levels between the two groups except for TSH concentration ( P <0.01). Total cholesterol, triglycerides and apolipoprotein (apo A1, A2, B) of women with subclinical hypothyroidism were not different from controls. HDL cholesterol was significantly decreased in subclinical hypothyroidism compared to the controls ( P <0.01). With thyroxine therapy, normalization of serum TSH was associated with (1) no significant change in total cholesterol and triglycerides, (2) an increase of HDL cholesterol ( P <0.01) and apoprotein Al ( P <0.05) levels. Total cholesterol/HDL cholesterol ratio was increased in subclinical hypothyroidism ( P <0.01). During L‐thyroxine therapy this ratio returned to normal value. Decreased HDL cholesterol concentration might cause coronary heart disease reported in women with subclinical hypothyroidism.Keywords:
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This study was undertaken at Biochemistry Department (BPKIHS) from 2001 to 2002. The aim of this study was to assess whether subclinical hypothyroidism is associated with abnormal cholesterol level in different age groups. Of the cases referred to the department, 398 euthyroid controls, 189 hypothyroid cases, 179 hyperthyroid cases and 181 subclinical hypothyroid cases were enrolled for further analyses. Both the sexes showed increased total cholesterol levels in hypothyroidism, and were not significantly changed in hyperthyroidism than in euthyroid controls. Female subclinical hypothyroid cases of age group 45-59 years and both the male and female cases of age group > or = 60 years had significantly (p < 0.01) elevated total cholesterol levels (196 +/- 37.36 mg/dl vs.169.37 +/- 29.12 mg/dl, 211.5 +/- 30.48 mg/dl vs. 151.54 +/- 55.84 mg/dl and 225 +/- 25.05 mg/dl vs. 181.73 +/- 32.95 mg/dl respectively) as compared to euthyroid controls. When data were analyzed at 33 and 45 years of age cut offs, the cases of > or = 33 years age in both hypothyroid male and female showed significantly (p < 0.01) elevated cholesterol levels (222.66 +/- 29.26 mg/dl vs. 156 +/- 37.09 mg/dl and 231.66 +/- 46.17 mg/dl vs 198.1 +/- 48.72 mg/dl respectively) where as subclinical hypothyroid female showed increased total cholesterol level (211 +/- 31.2 mg/dl vs. 157.95 +/- 45.92 mg/dl) at > or = 45 years age cut off. It is concluded that hypothyroidism not the hyperthyroidism is associated with increased total cholesterol level in the cases of this region, and we advise routine screening for cholesterol level in both the sexes of hypothyroid (for > or = 33 years) and female subclinical hypothyroid (for > or = 45 years) cases in this area, as they have high risk for higher cholesterol levels and developing related disorders.
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Background. We report the prevalence of symptomatic peripheral arterial disease (PAD) associated with subclinical hypothyroidism in older persons.
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Background Subclinical thyroid dysfunction — abnormal serum thyrotrophin (thyroid-stimulating hormone; TSH) concentrations with normal free thyroxine (FT4) is common in older people. It remains unclear whether individuals with subclinical serum status experience an increased symptom profile. Aim To compare the prevalence of those symptoms typically associated with overt thyroid dysfunction in older individuals with a subclinical and euthyroid serum profile. Design and setting Cross-sectional study, nested within the Birmingham Elderly Thyroid Study (BETS); from 19 UK general practices. Method Adults living in a community setting (aged ≥65 years), without overt thyroid dysfunction or associated treatment, self-reported the presence or absence of 18 symptoms (while serum result naïve). Serum concentrations of TSH and FT4 were measured to establish thyroid status. Results A total of 2870 individuals were screened: 2703 (94%) were categorised as euthyroid (normal), 29 (1%) subclinically hyperthyroid, and 138 (5%) subclinically hypothyroid. Symptoms were common in all groups. No significant differences in the prevalence of individual symptoms were observed between the euthyroid and subclinically hypothyroid groups nor in comparison with the subclinically hyperthyroid group. Multivariate logistic regression analysis failed to reveal an association between individual or multiple symptoms and subclinical status. Conclusion Findings suggest that subclinical thyroid dysfunction does not confer a symptom burden in older individuals and support adherence to guidelines in the non-treatment of subclinical thyroid dysfunction. GPs may use the findings to reassure older people presenting with symptoms that subclinical thyroid dysfunction is an unlikely explanation. The presence of persistently abnormal TSH concentrations may be linked to long-term risks of cardiovascular disease, especially atrial fibrillation, but whether this should prompt treatment and whether such treatment alters vascular outcomes is unknown.
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Objective To study the dynamic change of lipid metabolism in different thyroid function status during pregnancy.Methods This study recruited thirty cases of euthyroid,nineteen cases of subclinical hypothyroid and eight cases of subclinical hyperthyroid pregnancy.The concentrations of fasting serum total cholesterol(CHOL) and triglyceride(TRIG) were detected and analyzed at 9-12,14-17,23-26,and 37-40 gestational weeks.Results The statistical analysis showed that there were significant differences of maternal serum CHOL between subclinical hyperthyroid and euthyroid pregnancy,subclinical hyperthyroid and subclinical hypothyroid pregnancy(P 0.05).There was no significant difference between euthyroid and subclinical hypothyroid pregnancy(P 0.05).There was no significant difference of maternal serum TRIG among the three groups(P 0.05).Conclusion The concentrations of maternal CHOL and TRIG increased during pregnancy.The serum CHOL of subclinical hyperthyroid pregnancy was lower than that of euthyroid pregnancy.Concentrations of maternal serum CHOL was similar between euthyroid and subclinical hypothyroid pregnancy after treatment with drug.Different thyroid function status had no obvious effect on the metabolism of maternal TRIG.
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We report the prevalence of coronary artery disease (CAD) associated with subclinical hypothyroidism in older persons.We investigated the prevalence of subclinical hypothyroidism and its association with dyslipidemia and with CAD in 170 women and 110 men, mean age 75 +/- 9 years, in an academic nursing home.Of 280 persons, 18 (6%) had subclinical hypothyroidism, 18 (6%) had treated clinical hypothyroidism, 13 (5%) had subclinical hyperthyroidism, and 231 (83%) were euthyroid. Dyslipidemia occurred in 15 of 18 persons (83%) with subclinical hypothyroidism, in nine of 18 persons (50%) treated for hypothyroidism, in six of 13 persons (46%) with subclinical hyperthyroidism, and in 128 of 231 euthyroid persons (55%) (p <.025 comparing subclinical hypothyroidism with euthyroidism and p <.005 comparing subclinical hypothyroidism with treated hypothyroidism and with subclinical hyperthyroidism). CAD was present in 10 of 18 persons (56%) with subclinical hypothyroidism, in nine of 18 persons (50%) with treated hypothyroidism, in 5 of 13 persons (38%) with subclinical hyperthyroidism, and in 38 of 231 euthyroid persons (16%) (p <.001 comparing subclinical hypothyroidism with euthyroidism; p <.005 comparing treated hypothyroidism with euthyroidism; and p <.05 comparing subclinical hyperthyroidism with euthyroidism).Subclinical hypothyroidism was associated with a high prevalence of dyslipidemia and a high prevalence of CAD.
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Subclinical hypothyroidism is also known as mild hypothyroidism, early thyroid failure, preclinical hypothyroidism and decreased thyroid reserve. Subclinical hypothyroidism is defined as a high serum thyroid-stimulating hormone concentration and normal serum total or free thyroxine and triiodothyronine concentrations associated with few or no symptoms and signs of hypothyroidism and thus subclinical hypothyroid disease is diagnosed by laboratory findings.Subclinical hypothyroidism is far more common than overt hypothyroidism. The prevalence of subclinical hypothyroidism is relatively high and ranges from 4%-8.5% and maybe as high as 20% in women older than 60years. Subclinical hypothyroidism is more common in elderly women than men. It is found twice as often in women as in men. Thyroid hormones have a known effect on heart rate & cardiac excitability. Cardio vascular system is the major system affected by subclinical hypothyroidism. Subclinical hypothyroidism patients have an increased risk of “atherosclerosis” & coronary artery disease. Subclinical hypothyroidism patients will have an increased level of total cholesterol, triglyceride, low-density lipoprotein and decreased level of high-density lipoprotein, leading to “atherosclerosis”. This study was conducted totally on 110 human subjects of age group 18-60 years. Among the 110 human subjects, 55 were Euthyroid controls and 55 were subclinical hypothyroid cases. Serum total cholesterol, serum triglycerides, serum low-density lipoproteins, levels were increased in subclinical hypothyroid cases than Euthyroid controls with a high statistical significance with the P-value <0.001 and serum high-density lipoproteins levels are decreased in subclinical hypothyroid cases than Euthyroid controls with a high statistical significance with the P-value <0.001. Hence, it should be made mandatory that the estimation of lipid profile should be made as a routine investigation in all cases of subclinical hypothyroidism.
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Aim: Hypothyroidism is proved to be associated with atherosclerosis and cardio-vascular disease. But correlation between subclinical hypothyroidism (SCH) and increased cardiovascular risk is yet to be established. This study was done to investigate subclinical hypothyroidism and its associations with cardiovascular diseases.
Objectives: To quantitatively detect the levels of lipid profile parameters and range of blood pressure, in subclinical hypothyroid and euthyroid subjects. To correlate cardio vascular disease risk factors and their association with subclinical hypothyroidism.
Materials and Method: total sixty SCH cases and sixty euthyroid controls were compared. Serums levels of T3, T4, TSH were estimated by standard ELISA kit method, Serum LDL-Cholesterol using Friedewald equation, Triglycerides by GPO-POD with espas method, and Total-Cholesterol, HDL-Cholesterol by enzymatic CHOD-PAP by enzyme colorimetric method.
Result: Study showed increased mean serum levels of LDL Cholesterol, Total cholesterol, TSH, Triglycerides, systolic & diastolic BP. Serum levels of T4, HDL-Cholesterol remained normal. Number of people with increased Total Cholesterol, Triglycerides, LDL-C, systolic BP & diastolic BP and decreased HDL-C were more in subclinical hypothyroidism compared to euthyroid cases suggesting the dyslipidemic and hypertensive changes in SCH cases.
Conclusion: Study showed that cardio-vascular risk factors are highly associated with hypertension and dyslipidemic state seen in subclinical hypothyroidism cases, suggesting the higher association with subclinical hypothyroidism and risk factors of cardio-vascular disease.
Keywords: Euthyroid, Cardio-vascular risk, Sub-clinical hypothyroidism
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Overt hypothyroidism and hyperthyroidism are associated with hypertension, but it is uncertain whether the same is true of subclinical hypothyroidism and hyperthyroidism.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.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).Subclinical hypothyroidism is not associated with hypertension. The observed association between subclinical hyperthyroidism and hypertension requires confirmation in a larger sample.
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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.
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The widespread use of thyroid tests in asymptomatic individuals identifies many patients with transient subclinical hypothyroidism.Our objective was to determine the effect of seasonal change on serum TSH levels and the transition between subclinical hypothyroid and euthyroid status.This was a retrospective longitudinal study of 1751 subclinical hypothyroid and 28 096 euthyroid subjects aged over 18 years who underwent serial thyroid function tests at a health screening center between October 2003 and May 2011.Age-adjusted geometric mean values of the TSH level by month were calculated using linear mixed models. Adjusted odds ratios of test season and multiple baseline clinical factors were determined using generalized estimating equations.During a median 36 months of follow-up, 57.9% of subclinical hypothyroid subjects reverted to euthyroidism, and 4.3% of euthyroid subjects developed subclinical hypothyroidism. The monthly distribution of follow-up TSH levels indicated a biphasic pattern, ie, an increase during the winter-spring season and a decrease during the summer-fall season, with a maximal TSH difference of 0.69 mIU/L in subclinical hypothyroid and 0.30 mIU/L in euthyroid subjects. Normalization of subclinical hypothyroidism was increased 1.4-fold in follow-up tests during the summer-fall follow-up, whereas subclinical hypothyroidism increased 1.4-fold in euthyroid subjects during the winter-spring follow-up.The season in which thyroid testing was performed was independently related to the transition between subclinical hypothyroid and euthyroid status. Seasonal variations in TSH concentration should be considered before deciding on treatment of subclinical hypothyroidism, particularly in the areas with a wide annual temperature range.
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