Correlation Of A High Normal Serum TSH And TPOAb With Blood Pressure,Fasting Plasma Glucose And Dyslipidemia In Euthyroid Subjects

Objective Hypothyroidism is associated with cardiovascular Risk, Subclinical hypothyroidism’s diagnosis is based on an elevated serum TSH but normal FT4 levels, the correlation between subclinical hypothyroidism and cardiovascular adverse events have not yet unified. And there are few studies about the relationship between TSH levels within the normal range and TPOAb levels and cardiovascular risk factors. Purpose of this paper is to explore the association of a high normal serum TSH levels and TPOAb with blood pressure, fasting plasma glucose and dyslipidemia.Methods 1607 subjects completed a questionnaire survey and measurement for height, body weight, blood pressure, TSH, FPG, total cholesterol (TC), triglyceride (TG), and high-density lipoprotein cholesterol (HDL-C). body mass index (BMI) was calculated as weight/height2 expressed in kg/m2, LDL-C was calculated using the Friedewald formula:LDL-C=TC-HDL-C-TG/2.2 (mmol/L), ①According to the level of TSH the subjects were divided into low TSH group(0.30-0.99 mIU/L, n=351), moderate TSH group(1.00-1.89 mIU/L, n=703) and high TSH group(1.90-4.80 mIU/L, n=456). Analysis of variance and linear regression were used for data analysis. ②All subjects were divided into 2 groups according to the level of TPOAb:TPOAb-positive group (TPOAb≥5.61 IU/mL, n=205) and TPOAb-negative group (TPOAb＜5.61 IU/mL, n=1402). We then subgrouped the subjects according to serum TSH levels; subjects with a TSH level of 0.3-0.99 mIU/L,1.0-1.89 mIU/L and 1.9-4.80 mIU/L were classified into the low-normal, mid-range, and high-normal TSH subgroups, respectively. Each TSH group was subdivided further into TPOAb-positive and TPOAb-negative subgroups. A t-test was used to compare group means.Results1. For all people, SBP(P=0.009), DBP (P=0.003), TG(P=0.028) and HDL-C(P=0.009) had significant differences among the low TSH group, moderate TSH group and high TSH group, In the univariate linear regression model, Serum TSH within the reference range was negatively associated with SBP(β=-3.743, P=0.015) and DBP(β=-3.036, P=0.006); positively associated with TG(β=0.195, P=0.002) and HDL-C(β=0.125, P=0.016) however, after adjustment for gender, age, body mass index(BMI), FPG, TC, the correlations were no longer present.2. For females, In the univariate linear regression model, Serum TSH within the reference range was positively associated with TG(β=0.222, P=0.002), In the multiple linear regression model, however, after adjustment for gender, age, body mass index(BMI), FPG, TC, the correlations were no longer present.3. For males, In the multiple linear regression model, a significant negative correlation was found between normal range TSH, SBP(β=-7.244, P=0.021), FPG(β=-0.407, P=0.036).4. For all people, Compared to TPOAb-negative subjects, TPOAb-positive patients had higher levels of TSH, TC, and HDL-C (P=0.001, P=0.012, and P=0.049, respectively) and a tendency for increased LDL-C levels (P=0.053); BMI, BP, FPG, TG levels were not significantly different between groups.5. In the low-normal TSH subgroup, BMI, SBP, DBP, and levels of TSH, FPG, TC, TG, LDL-C, and HDL-C were not significantly different TPOAb-positive patients TPOAb-negative subjects.6. In the mid-range TSH subgroup, TPOAb-positive patients had higher HDL-C levels (P=0.008) and a tendency for increased TC levels (P=0.121) compared to TPOAb-negative subjects; the TSH, BMI, BP, FPG, TG and LDL-C levels were not significantly different between groups.7. In the high-normal TSH subgroup, the TSH and TC levels were higher in TPOAb- positive patients compared to TPOAb-negative subjects, (P<0.001 and P=0.046, respectively), and BMI, BP, FPG, TG, LDL-C, and HDL-C levels were not significantly different between groups.Conclusion1. Euthyroid subjects, different TSH levels within the normal range, different blood pressure, lipid levels.2. In male population, serum TSH levels within the normal range are negatively correlated with SBP, FPG.3. High TPOAb levels above the normal range appears in euthyroid population, dyslipidemia have begun, BMI, BP, FPG levels were not significantly different.