RESUMEN
BACKGROUND@#Thyroid dysfunction is associated with cardiovascular diseases. However, the role of thyroid function in lipid metabolism remains partly unknown. The present study aimed to investigate the causal association between thyroid function and serum lipid metabolism via a genetic analysis termed Mendelian randomization (MR).@*METHODS@#The MR approach uses a genetic variant as the instrumental variable in epidemiological studies to mimic a randomized controlled trial. A two-sample MR was performed to assess the causal association, using summary statistics from the Atrial Fibrillation Genetics Consortium (n = 537,409) and the Global Lipids Genetics Consortium (n = 188,577). The clinical measures of thyroid function include thyrotropin (TSH), free triiodothyronine (FT3) and free thyroxine (FT4) levels, FT3:FT4 ratio and concentration of thyroid peroxidase antibodies (TPOAb). The serum lipid metabolism traits include total cholesterol (TC) and triglycerides, high-density lipoprotein, and low-density lipoprotein (LDL) levels. The MR estimate and MR inverse variance-weighted method were used to assess the association between thyroid function and serum lipid metabolism.@*RESULTS@#The results demonstrated that increased TSH levels were significantly associated with higher TC (β = 0.052, P = 0.002) and LDL (β = 0.041, P = 0.018) levels. In addition, the FT3:FT4 ratio was significantly associated with TC (β = 0.240, P = 0.033) and LDL (β = 0.025, P = 0.027) levels. However, no significant differences were observed between genetically predicted FT4 and TPOAb and serum lipids.@*CONCLUSION@#Taken together, the results of the present study suggest an association between thyroid function and serum lipid metabolism, highlighting the importance of the pituitary-thyroid-cardiac axis in dyslipidemia susceptibility.
Asunto(s)
Metabolismo de los Lípidos/genética , Análisis de la Aleatorización Mendeliana , Pruebas de Función de la Tiroides , Glándula Tiroides , Tirotropina , Tiroxina , TriyodotironinaRESUMEN
<p><b>BACKGROUND</b>Previous studies have suggested that hypothyroidism correlated with coronary heart diseases (CHD) mortality in long-term cohort, but whether the thyroid function status is associated with myocardial injury in acute ST-elevation myocardial infarction (STEMI) has not been investigated sufficiently.</p><p><b>METHODS</b>Five hundred and eighty-two hospitalized patients from January 2010 to December 2011, with the diagnosis of STEMI, were enrolled in this study. All patients underwent testing for thyroid function status, cardiac troponin I (cTnI), cardiac enzymes, C-reactive protein (CRP). We investigated the association between thyroid hormone levels and cardiac markers (creatine kinase-MB and cTnI), and thus evaluated the potential role of thyroid function status in predicting the myocardial injury.</p><p><b>RESULTS</b>There were 76 patients (13.06%) who had hypothyroidism including low-T3-syndrome (34 patients, 5.84%), subclinical hypothyroidism (28 patients, 4.81%) and clinical hypothyroidism (14 patients, 2.41%). After adjusting for conventional risk factors (age, gender, smoking, diabetes mellitus, dyslipidemia, hypertension), free triiodothyronine (FT3) was significantly and negatively correlated with log-CKMB (r = -0.244, P < 0.001) and log-cTnI (r = -0.290, P < 0.001), indicating that the lower thyroid hormone level correlates with the severer cardiac injury in STEMI patients. FT3 also had a moderate negative correlation with CRP (r = -0.475, P < 0.001), which might indicate that hypothyroidism may activate the inflammation response. No significant correlation was found between other thyroid parameters (TSH, FT4) and cardiac markers.</p><p><b>CONCLUSIONS</b>As the lower FT3 level correlates with higher level of cardiac markers and lower left ventricular ejection fraction (LVEF), the hypothyroidism may be a predictor for myocardial injury in STEMI. And these results may warrant further study to investigate whether reversing the hypothyroidism could benefit the STEMI patients.</p>