To evaluate the prevalence of
dyslipidemia in the population of
Hashimoto thyroiditis, we reviewed medical records on the consecutive 1181 cases with adult
Hashimoto thyroiditis and 830 cases were adopted for the study. First, the serum TSH level increased and serum free T4 level decreased, slightly but significantly, with increasing age. There were significant positive correlations between serum TSH levels and
lipid parameters such as total
cholesterol (TC),
triglyceride (TG),
HDL-cholesterol (HDL-C),
LDL-cholesterol (
LDL-C), non-HDL-C and
LDL-C/HDL-C ratio (L/H). In contrast, there were significant negative correlations between serum free T4 levels and all of these
lipid parameters. According to the thyroid function, the cases were classified into 4 groups such as
thyrotoxicosis (TT), euthyroidism (EU), subclinical
hypothyroidism (SH) and overt
hypothyroidism (
OH). TC, HDL-C, non-HDL-C and
LDL-C of TT were significantly lower than those in EU. In contrast, TC, TG, non-HDL-C,
LDL-C, L/H and age of
OH were significantly higher than those in EU. Interestingly,
LDL-C and L/H of SH were significantly higher compared with EU. Thirty-two of SH patients were treated with small doses of
levothyroxine and the effects on the
lipid profile were examined. The TC, non-HDL-C,
LDL-C and L/H were significantly decreased
after treatment. In conclusion, the prevalence of
dyslipidemia increases along with hypofunction of the thyroid and T4 replacement
therapy may improve
lipid profile in the cases of SH with
Hashimoto thyroiditis.