Thyroid function and PCSK9 in euthyroid subjects with coronary artery disease

Background: Both thyroid hormone and PCSK9 are key regulators of lipid metabolism. Their respective impacts on dylipidemia and the development of associated coronary artery disease (CAD) have received continued interest. Aim: To examine whether plasma PCSK9 levels were correlated with thyroid hormones in euthyroid subjects with stable CAD. Materials & methods: A total of 447 euthyroid subjects with stable CAD were prospectively enrolled. Angiography and lipid-lowering therapy were parts of the screening process. Baseline clinical characteristics were collected. Fasting free triiodothyronine (FT3), free thyroxine (FT4), thyrotropin (TSH), glucose and lipid profiles were measured. Plasma PCSK9 levels were determined by ELISA. Results: Plasma PCSK9 levels exhibited an inverse correlation with FT3 (r = -0.182, p < 0.001) and a positive correlation with TSH (r = -0.100, p = 0.035). After adjustment for cardiometabolic risk factors, patients with higher levels of PCSK9 differed from those with lower levels of PCSK9 in FT3, FT4 and TSH levels (p < 0.05, all). When Logistic analysis was performed with PCSK9 tertiles as the dependent variable, FT3 (OR = 0.430, 95% CI: 0.206-0.897), FT4 (OR = 0.863, 95% CI: 0.708-0.995) and TSH (OR = 2.114, 95% CI: 1.003-4.457) exhibited independent associations with an elevated PCSK9 level (tertile 3). Finally, multiple linear analysis revealed that PCSK9 levels were related significantly and independently to FT3 (beta = -0.110, p = 0.019) but not FT4 (beta = -0.073, p = 0.110) or TSH (beta = -0.087, p = 0.060). Conclusion: The study demonstrates a negative association between thyroid function and PCSK9 levels in euthyroid subjects with stable CAD, suggesting a potential interaction between PCSK9 and lower levels of thyroid hormones in patients with CAD.