Objective: We aimed at demonstrating the effect of thyroid function status on proprotein convertase subtilisin kexin type 9 (PCSK9) and determining the effect of thyroid hormones on lipid metabolism by comparing the PCSK9 levels of patients with subclinical hypothyroidism, overt hypothyroidism, and hyperthyroidism.
Patients and methods: 124 patients with thyroid disorders, aged between 18 and 65 years, were included in this study. The participants were divided into 3 groups. Group 1 comprised 52 patients with subclinical hypothyroidism, Group 2 comprised 40 patients with overt hypothyroidism, and Group 3 comprised 32 patients with hyperthyroidism. In all of these groups, the thyroid-stimulating hormone (TSH), free triiodothyronine (fT3), free thyroxine (fT4), low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, triglyceride, total cholesterol, fasting serum glucose, antithyroid peroxidase antibody, antithyroglobulin antibody, and PCSK9 levels were measured.
Results: No significant difference was found between the 3 groups in terms of age, gender, and body mass indices. Median PCSK9 measurements were 14.55 ng/mL in Group 1, 14.895 ng/mL in Group 2, and 9.775 ng/mL in Group 3. There was a significant difference in the PCSK9 levels between Group 1-Group 3 and Group 2-Group 3 (p <0.0001 and p <0.0001, respectively). A positive correlation between PCSK9 and the TSH levels (r = 0.211, p= 0.019), and a negative correlation (r = -0,239, p = 0.009 and r = -, 0.218, p = 0.015) between the fT3 and fT4 levels were found.
Conclusions: The serum PCSK9 levels were shown to be associated with thyroid dysfunction. However, no relationship was observed between the serum PCSK9 level and thyroid autoantibody positivity, and obesity in this study.