Abstract Disclosure: C. Neves: None. J. Neves: None. L. Pereira: None. O. Sokhatska: None. J. Queirós: None. J. Delgado: None. Background: Autoimmune thyroiditis is one of the most common organ specific autoimmune disorders. Several studies suggest that patients with autoimmune thyroid may have an increased cardiovascular risk even among those with normal thyroid function. Our objective was to evaluate the cardiovascular risk factors in autoimmune thyroiditis according to body weight. Methods: We evaluated patients with autoimmune thyroiditis followed in outpatient clinic. We evaluated anthropometric parameters, glycemic profile, lipid, homocysteine, folic acid, B12 vitamin, high-sensitivity C reactive protein (hsCRP), thyroid function and thyroid autoimmunity. Participants were divided in groups according to body weight: normal weight [body mass index (BMI) 18.5-24.9 kg/m2], overweight (BMI 25.0-29.9 kg/m2) and obesity (BMI ≥30 kg/m2). Correlations were evaluated in the whole group and in subgroups of body weight. Statistical analysis was performed with the one-way ANOVA test and Pearson’s correlation test. Results: Within our sample of 354 patients had autoimmune thyroid, 93.8% were females, with a mean age of 46.7±16.3 years. One-hundred and three (37.6%) had normal weight, 128 (36.1%) had overweight and 91 (25.7%) had obesity. The mean TSH level of our population was 2.5±6.0 μUI/L. In our sample, TSH, FT4 and FT3 did not significantly differed between body weight groups. Comparing with normal weight, patients with obesity and overweight had higher fasting glucose (normal weight 92±13 mg/dL vs overweight 91±23 mg/dL vs 92±13 mg/dL, p= 0.004), higher LDL levels (normal weight 112.7±29.2 mg/dL vs overweight 130.1±29.4 mg/dL vs obesity 130.6±31.3mg/dL, p<0.001), higher triglycerides (normal weight 94.8 ± 43.0 mg/dL vs overweight 120.1 ± 79.0 mg/dL vs obesity 140.5 ± 80.4 mg/dL, p<0.001) and higher hsCRP levels (normal weight 0.3±0.5 mg/dL, overweight 0.4±0.5 mg/dL vs obesity 0.5±0.6 mg/dL, p=0.018). In the whole group, TSH was positively correlated with insulin (r=0.184, p=0.003), C-peptide (r=0.187, p=0.003) and HOMA-IR (r=0.178, p=0.004); anti-TG was negatively correlated with HDL (r= -0.147, p=0.006), and anti-TPO was positively correlated with LDL cholesterol (r=0.134, p=0.013) and with HOMA-IR (r= 0.126, p=0.039). In patients with normal weight anti-TG was negatively correlated with fasting glycemia (r=-0.204, p=0.046). In patients with overweight, anti-TG was positively correlated with hsCRP (r= 0.187, p= 0.043). In patients with obesity, TSH was positively correlated with C-peptide (r=0.280, p=0.020) and triglycerides (r=0.258, p= 0.016); and anti-TPO was correlated with fasting insulin levels (r=0.282, p=0.018). Conclusions: In patients with autoimmune thyroiditis, the interrelationships between thyroid function, autoimmunity, obesity, insulin resistance and lipid profile may contribute to the increased cardiovascular risk. Presentation: 6/3/2024