Thyroid dysfunction and serum lipids: A community-based study

Sir Charles Gairdner Hospital, Perth City, Western Australia, Australia
Clinical Endocrinology (Impact Factor: 3.46). 12/2005; 63(6):670-5. DOI: 10.1111/j.1365-2265.2005.02399.x
Source: PubMed


It is uncertain whether subclinical hypothyroidism (SCH) is associated with hypercholesterolaemia, particularly in subjects with SCH and serum TSH < or = 10 mU/l. Design,
Cross-sectional study of 2108 participants in a 1981 community health survey in Busselton, Western Australia. Serum total cholesterol and triglycerides were measured in all subjects and high density lipoprotein cholesterol (HDL-C) measured (and low density lipoprotein cholesterol (LDL-C) calculated) in a subgroup of 631 subjects at the time of the survey. In 2001, TSH and free T4 concentrations were measured on archived sera stored at -70 degrees C. Serum lipid concentrations in subjects with thyroid dysfunction and euthyroid subjects were compared using linear regression models.
In the group as a whole, serum total cholesterol was higher in subjects with SCH (N = 119) than in euthyroid subjects (N = 1906) (mean +/- SD 6.3 +/- 1.3 mmol/l vs. 5.8 +/- 1.2 mmol/l, P < 0.001 unadjusted, P = 0.061 adjusted for age, age(2) and sex). Serum total cholesterol was similarly elevated in subjects with SCH and TSH < or = 10 mU/l (N = 89) (6.3 +/- 1.3 mmol/l, P < 0.001 unadjusted, P = 0.055 adjusted for age, age(2) and sex). In the subgroup analysis, LDL-C was higher in subjects with SCH (N = 30) than in euthyroid subjects (N = 580) (4.1 +/- 1.2 mmol/l vs. 3.5 +/- 1.0 mmol/l, P < 0.01 unadjusted, P = 0.024 adjusted for age, age(2) and sex). LDL-C was significantly increased in subjects with SCH and TSH < or = 10 mU/l (N = 23) (4.3 +/- 1.3 mmol/l, P < 0.001 unadjusted, P = 0.002 adjusted for age, age(2) and sex).
SCH is associated with increased serum LDL-C concentrations, which is significant after adjustment for age, age(2) and sex.

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Available from: Max Bulsara, Sep 08, 2015
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    • "Smoking is a potential modifier of the association between thyroid status and serum lipids; serum LDL-C and TC are approximately 25% higher in hypothyroid smokers compared to hypothyroid nonsmokers (19). HDL-C has been variably reported to be low or unchanged in SCH (6, 18). We found no effect of SCH on mean HDL-C. "
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    ABSTRACT: Background:Overt hypothyroidism is associated with abnormalities of lipid metabolism, but conflicting results regarding the degree of lipid changes in subclinical hypothyroidism (SCH) exist.Objectives:The aim of this study was to assess differences in lipid profile parameters between subjects with and without SCH in a north Indian population.Patients and Methods:Serum lipid parameters of 70 patients with subclinical hypothyroidism and 100 age and sex matched euthyroid controls were evaluated in a cross-sectional study.Results:Mean serum total cholesterol (TC), triglycerides (TG) and very low-density cholesterol (VLDL) were significantly higher in patients with SCH than controls (P < 0.05). Mean TC, TG and low-density cholesterol (LDL) concentrations were higher in patients with serum thyroid stimulating hormone (TSH) greater than 10 mU/L than those with serum TSH equal to or less than 10 mU/L, but this difference was not statistically significant. No association was found between serum high-density cholesterol (HDL-C) concentration and serum TSH level.Conclusions:High TC, TG and VLDL were observed in our patients with SCH.
    Full-text · Article · Jul 2014 · International Journal of Endocrinology and Metabolism
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    • "TC and LDL became significantly elevated in subjects with SCH-2 compared with controls and subjects with SCH-1. Others have also shown that elevation of TC was more evident in patients with TSH N 10 mIU/L [3] [4] [26]. In a recent study, a correlation was also noted between age, TSH and LDL with carotid intima media thickness (CIMT) in patients with SCH [27]. "
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    ABSTRACT: In view of inconsistent reports on the prevalence of dyslipidemia in subclinical hypothyroidism (SCH), we studied lipid abnormalities in Indian subjects with SCH. A cross sectional study of 5343 subjects divided in two groups, Group-1 (age≤18 years) and Group-2 (age>18 years) was undertaken. They were further subdivided on the basis of their thyroid functional status: Normal (Control); SCH with TSH≤10.0mIU/L (SCH-1); and SCH with TSH>10mIU/L (SCH-2). Prevalence of SCH was 14.7%. The only lipid abnormality in children and adolescents was low HDL in subjects with TSH>10mIU/L compared with controls. Serum total cholesterol (TC), and LDL cholesterol (LDL) were significantly higher in adults with TSH>10mIU/L compared to controls. There were no significant changes in lipid parameters in subjects with SCH having TSH≤10.0mIU/L, compared to controls. Serum TSH was positively and FT3 and FT4 were negatively correlated with TC and LDL. Atherogenic lipid abnormalities were observed in adult subjects with SCH-2 (TSH>10.0mIU/L), and not in subjects with SCH-1 who had TSH≤10.0mIU/L in Indian population.
    Full-text · Article · Jul 2011 · Clinical biochemistry
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    • "In the New Mexico Elder Health survey, although no significant increase of TC, HDLc and triglycerides value was observed in sHT patients, women with serum TSH >10 mIU/L had LDLc and HDLc higher than euthyroid subjects [107]. At variance, in the community-based study from Busselton, including 2108 subjects, both serum TC and LDLc levels were significantly higher in sHT patients than in euthyroid subjects [153]. Moreover, in a cross-sectional study of a general population from a Danish primary health care centre, sHT patients had significantly higher serum triglyceride levels than euthyroid controls [102]. "
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    ABSTRACT: Endothelial dysfunction represents an important pathway thereby cardiovascular risk factors promote the development and progression of atherosclerosis. Hypothyroidism is associated with an increased cardiovascular risk, and the assessment of endothelium function is recognised an effective tool for the detection of evidence of preclinical cardiovascular alterations. Both vascular smooth muscle cells and endothelium play pivotal roles in modulating vascular tone and both are potential targets of thyroid hormone action. The pathogenesis of the association between endothelial dysfunction and hypothyroidism is complex and still not well established. The presence of traditional and emerging risk factors may contribute to the development of endothelium impairment, generating a chronic state of injury that triggers abnormal endothelial response. Levothyroxine replacement therapy is currently used for restoring euthyroidism and improving cardiovascular risk of hypothyroid patients. The decision to treat patients with subclinical hypothyroidism should depend on the presence of risk factors, rather than on a TSH threshold. However, the actual effectiveness of thyroid hormone substitution in reducing the risk of cardiovascular events, especially in subclinically hypothyroid patients, remains to be elucidated. Large multicenter, placebo-controlled prospective trials are necessary to address the issue. The article also discusses recent patents in this field.
    Full-text · Article · May 2008 · Recent Patents on Endocrine Metabolic & Immune Drug Discovery
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