Association Between Thyroid Hormones, Thyroid Antibodies, and Cardiometabolic Factors in Non-Obese Individuals With Normal Thyroid Function

Abstract

BackgroundHypothyroidism is an important risk factor for cardiovascular diseases, and autoimmune thyroiditis (AIT) is the leading cause of hypothyroidism. Recent studies showed that even AIT patients with euthyroidism still had an increased number of early atherosclerotic lesions. However, the precise mechanism is not yet known. This study aimed to investigate the association of thyroid function, thyroid autoimmunity, and cardiometabolic risk factors in non-obese AIT patients with euthyroidism.MethodsA total of 5,608 non-obese individuals including 1,402 AIT patient and 4,206 sex-, age-, and body mass index (BMI)-matched healthy controls were recruited.ResultsThe AIT patients had significantly lower free T3 and free T4 levels, and higher TSH, antithyroid peroxidase antibodies (TPOAb) and TgAb levels. The elevated levels of high sensitivity C reactive protein (hsCRP) and homeostasis model assessment of insulin resistance (HOMA-IR) were observed in the AIT patients than the controls [hsCRP: 0.65 (0.27–1.33) vs. 0.20 (0.03–0.74) mg/L; HOMA-IR: 2.78 ± 1.60 vs. 2.33 ± 1.49; all P < 0.05]. Thyroid function was not associated with metabolic parameters and inflammatory makers, while the TPOAb titer was positively associated with the HOMA-IR and hsCRP levels after adjustment for confounding factors (all P < 0.05). Multivariate regression analysis demonstrated that the TPOAb level was an independent influencing factor for the HOMA-IR and hsCRP levels (HOMA-IR: β = 0.058, P < 0.05; hsCRP: β = 0.108, P < 0.05).ConclusionThe TPOAb level is associated with HOMA-IR and hsCRP levels independently of thyroid function in non-obese individuals. Mild deviation of thyroid function within the normal range, chronic inflammation, and insulin resistance may be the links between AIT and atherosclerosis in the non-obese population.

The Relationship Between the Impairment of Endothelial Function and Thyroid Antibodies in Hashimoto’s Thyroiditis Patients with Euthyroidism

“…It is also the most sensitive marker for Hashimoto's thyroiditis and associate with the degree of infiltration by lymphocytes. TPOAb is able to induce and activate the complement system and exert the cellular cytotoxicity [17]. In the previous studies, TPOAb levels were positively related to the C reactive protein and multiple pro-inflammatory cytokines such as TNF-α, interleukin-6, and interferon-γ [22].…”

“…In the previous studies, Hashimoto's patients had increased C reactive protein, interleukin 6, interleukin 1β, and tumor necrosis factor α levels. It is suggested that Hashimoto's patients were in the state of chronic inflammation [16,17]. In addition, Hashimoto's patients also had higher levels of soluble intercellular adhesion molecule 1 (sICAM-1) and soluble vascular cell adhesion molecule-1 (sVCAM-1) although they were in the euthyroidism states [18].…”

Does Hashimoto's Thyroiditis Increase the Risk of Cardiovascular Disease in Young Type 1 Diabetic Patients?

“…The scientific research on the relevance of low-normal thyroid function on components of the metabolic syndrome (MS) shows that the state is significantly associated with all components of MS (34). Several studies in obese and also in non-obese individuals, with thyroid function at normal range, presented the results of association between elevated thyroid antibodies with insulin resistance and hsCRP (16,35). Low-normal thyroid function may be implicated into atherosclerosis development via connections with insulin resistance and metabolic syndrome (36).…”

Thyroid Peroxidase Revisited – Whatʼs New?

“…Detection of TPOAbs during pregnancy can predict the development of post-partum thyroiditis [49]. Increased interest has been focused on the association between thyroid function and metabolic disorders in euthyroid individuals [55,56]. For example, Liu et al have recently shown that TPOAbs level is associated with cardiometabolic risk factors in non-obese euthyroid individuals [56].…”

“…Increased interest has been focused on the association between thyroid function and metabolic disorders in euthyroid individuals [55,56]. For example, Liu et al have recently shown that TPOAbs level is associated with cardiometabolic risk factors in non-obese euthyroid individuals [56]. Another widely discussed issue is the connection between thyroid antibodies and cancer [57][58][59].…”