Risk Factors for Cardiovascular Disease in Women with Subclinical Hypothyroidism

Abstract

Overt hypothyroidism may result in accelerated atherosclerosis and coronary heart disease (CHD) presumably because of the associated hypertension, hypercholesterolemia, and hyperhomocysteinemia. As many as 10%-15% of older women have subclinical hypothyroidism (SH) and thyroid autoimmunity. Whether SH is associated with risk for CHD is controversial. We examined 57 women with SH and 34 healthy controls. SH was defined as an elevated thyrotropin (TSH) (>4.5 mU/L) and normal free thyroxine (FT(4)) level (8.7-22.6 nmol/L). None of the patients had been previously treated with thyroxine. In all participants we determined blood pressure, body mass index (BMI), and fasting TSH, FT(4), antibodies to thyroid peroxidase and thyroglobulin, total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), triglycerides, folic acid, vitamin B(12), creatinine, and total plasma homocysteine levels. The SH and control groups did not differ in their total homocysteine values. Mean diastolic blood pressure was increased in SH patients versus controls (82 vs. 75 mm Hg; p < 0.01). Mean values of TC, HDL-C, LDL-C, triglycerides, TC/HDL-C, and LDL-C/HDL-C were not different in patients with SH compared with controls. Individual analysis revealed that the percentage of patients with SH having hypertension (20%), hypertriglyceridemia (26.9%), elevated TC/HDL-C (11.5%), and LDL-C/HDL-C (4%) ratios were higher than the percentages in controls. Hyperhomocysteinemia (> or = 10.98 micromol/L) was observed in 29.4% of SH and was not significantly different from the percentage in controls (21.4%). No significant correlation between TSH and biochemical parameters was detected. We conclude that subclinical hypothyroidism in middle-aged women is associated with hypertension, hypertriglyceridemia, and elevated TC/HDL-C ratio. This may increase the risk of accelerated atherosclerosis and premature coronary artery disease in some patients.

Prevalence of subclinical hypothyroidism in adults visiting primary health-care setting in Riyadh

“…This finding is partially consistent with findings of Busselton Thyroid Study, which concluded that subclinical hypothyroidism is not associated with hypertension [19]. However, in another study on women, subclinical hypothyroidism was found to be associated with diastolic hypertension, hypertriglyceridemia, and increase in BMI [26]. In our study, we did find higher TSH level to be associated with presence of hyperlipidemia in the patients; however, this association was not statistically significant ( p  = .076).…”

TSH and free thyroxine concentrations are associated with differing metabolic markers in euthyroid subjects

“…SCH is defined as a mild elevation of TSH and normal levels of free thyroid hormones. The association between SCH and individual cardiovascular risk factors has also been explored, with discordant results (4)(5)(6). Even more controversial is the association between SCH and insulin resistance (7).…”

Multi-center study on the prevalence of hypothyroidism in patients with hypercholesterolemia

“…Increasing evidences indicate that subclinical hypothyroidism is also related to dyslipidemia and T4 treatment of this condition may improve the lipid profile of the patients [11,12]. Consequently, subclinical hypothyroidism is associated with an increased risk of coronary heart disease [13,14] and with increased coronary heart disease events and cardiovascular deaths [15].…”