Decrease in Serum Levels of Thyroid Hormone in Patients with Coronary Heart Disease.

Abstract

Abstract. The aim of this study was to evaluate the relationship between subclinical hypothyroidism and/or autoimmune thyroid disease and coronary heart disease (CHD). Ninety seven patients diagnosed as having CHD by a coronary angiography (CHD group) and 103 healthy subjects matched for age, sex and body mass index (control group) were included in the study. Thyroid function, thyroid autoantibodies and serum lipid concentrations were measured in the CHD and control groups. The CHD group exhibited significantly decreased serum free T3 (FT3) and free T4 (FT4) levels, and significantly increased serum TSH levels as compared with the control group, indicating a significant decrease in thyroid function in the CHD patients. Serum high density lipoprotein cholesterol (HDL-C) levels were significantly decreased in the CHD group. The incidence of subclinical hypothyroidism and thyroid autoantibodies was similar in both two groups. These observations were also true of women even after those who had diabetes mellitus (DM), hypertension (HT) and a smoking habit were excluded. This was not the case, however, in men without DM, HT, or a smoking habit. Patients with CHD had significantly lower serum levels of HDL-C than the control subjects, regardless of gender (P<0.01). In the group with CHD, there was no difference between the serum lipid levels in patients with subclinical hypothyroidism and those with normal thyroid function. Female patients with CHD had significantly lower serum levels of thyroid hormone and HDL-C, but their subclinical hypothyroidism or thyroid autoimmunity did not seem to be related to the development of CHD.

The Association of Thyroid Function and Heart Valve Sclerosis. Results from a Population-Based Study

“…Our findings are at least in part in line with previous studies that found an association between hypothyroidism and an elevated risk for coronary artery disease in both males and females [9,10]. In contrast, certain cross-sectional studies could not confirm an association of hypothyroid function and atherosclerosis [19][20][21].…”

The association of thyroid function with carotid artery plaque burden and strokes in a population-based sample from a previously iodine-deficient area

“…In addition, some studies have demonstrated an association between thyroid autoimmunity and coronary heart disease in (subclinical) hypothyroidism (35-37), while we did not find any association between TPO antibody positivity itself, carotid plaque formation and serum TSH levels in any direction. For low TSH values, this is in line with a previous study that could not confirm an association between thyroid antibodies and atherosclerosis in hypothyroid subjects (5,38,39). Regarding the association of low serum TSH levels, carotid plaque formation, and prevalent stroke, the interpretation is much more complex.…”

The relationship between thyroid stimulating hormone within the reference range and coronary artery disease: impact of age

“…Studies on the relationship between normal range of thyroid function and CAD had produced inconsistent results [10][11][12][13][14][15]. The discrepancies might derive from the number of enrollment, heterogenous subjects and racial difference et al However, the effect of age on this relationship was neglected and none of them performed an age-stratified analysis.…”

“…One prospective study indicated TSH levels within the reference range were positively and linearly associated with cardiovascular mortality in women [9] and four cross-sectional studies [10][11][12][13] reported that relatively low thyroid function within the reference range was associated with the presence of CAD, while two others [14][15] did not confirm these findings. These results arouse the debate on whether there is a need to redefine the upper normal limit of TSH [16][17].…”