Serum cholesterol levels in middle-aged euthyroid subjects with positive thyroid peroxidase antibodies

This study was designed to investigate serum cholesterol levels in middle-aged euthyroid subjects with positive thyroid peroxidase antibodies (TPOAbs).

We screened 1607 euthyroid subjects aged 35-65 years old. All the subjects were divided into 2 groups (i.e., TPOAb-positive group, n=205; TPOAb-negative group, n=1402) according to the level of TPOAb. The subjects were then subgrouped according to serum thyroid stimulating hormone (TSH) levels; those 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 further subdivided into TPOAb-positive and TPOAb-negative subgroup. Data regarding the subjects' height, body weight, blood pressure, and levels of serum TSH, TPOAb, fasting plasma glucose, total cholesterol (TC), triglyceride (TG), low density lipoprotein cholesterol (LDL-C), and high density lipoprotein cholesterol (HDL-C) were collected.

Compared with 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) with a tendency for increased LDL-C levels (P=0.053). In the low-normal TSH subgroup, subjects with and without TPOAb had similar levels of TSH, TC, HDL-C, and LDL-C (P>0.05). In mid-range TSH subgroup, TPOAb-positive patients had higher HDL-C levels compared to TPOAb-negative subjects (P=0.008) and a tendency for increased TC levels (P=0.121). In the high-normal TSH subgroup, TPOAb-positive patients had higher TSH and TC levels compared to TPOAb-negative subjects (P<0.001 and P=0.046 respectively).

High TPOAb levels above the normal range appears in euthyroid population, dyslipidemia have begun.