The relationship between cholesterol levels and thyroid eye disease.

Background: Thyroid eye disease (TED) is the most prevalent extrathyroidal manifestation of Graves' disease (GD). Emerging evidence suggests a relationship between elevated total and low-density lipoprotein (LDL) cholesterol levels and TED. This study aimed to investigate this correlation in the Brazilian population by analyzing data from two tertiary care centers.

Methods: Data were collected from GD patients treated with methimazole between 1999 and 2021, excluding those receiving other treatments. Laboratory results and information on smoking habits, statin use and medications affecting lipid profiles during the euthyroid state were analyzed.

Results: Smoking and elevated LDL cholesterol levels were significantly associated with TED activity and severity. Logistic regression revealed correlations between higher LDL cholesterol, total cholesterol and increased clinical activity score (P < 0.01, OR: 1.012, 95% CI: 1.003-1.021; P < 0.01, OR: 1.010, 95% CI: 1.002-1.018). These were also associated with more severe disease forms as defined by EUGOGO (P < 0.01, OR: 1.015, 95% CI: 1.006-1.024; P < 0.005, OR: 1.011, 95% CI: 1.004-1.019). Multiple regression confirmed that TED activity was significantly correlated with LDL cholesterol (P < 0.01) and smoking status (P < 0.01). Disease severity was associated with reduced HDL cholesterol (P < 0.05, OR: 0.973, 95% CI: 0.948-0.999), elevated LDL cholesterol (P < 0.005, OR: 1.013, 95% CI: 1.004-1.023) and active smoking (P < 0.05, OR: 2.881, 95% CI: 1.190-6.971).

Conclusion: Elevated LDL cholesterol may serve as a potential indicator of TED. Further research is needed to determine whether lipid-lowering interventions could reduce TED risk or improve its management.