Endocrine Abstracts

Aim: The aim of this study was to evaluate the association between thyroid function in Graves’ disease (GD) with high-sensitivity C-reactive protein (hs-CRP), lipid profile, homocysteine, folate, vitamin B12 and insulin resistance.

Methods: We performed a cross-sectional of 104 patients with recently diagnosed GD. All participants were in the first cycle of treatment with methimazole. We collected demographic information, body mass indexes (BMI), laboratory data including thyroid function tests (TSH, FT3 and FT4), antithyroid antibodies levels (TRAb, anti-TPO and anti-thyroglobulin), lipid profile, hs-CRP, homocysteine, folate, vitamin B12 and insulin sensitivity indexes obtained from a 75 g OGTT. Statistical analysis was performed using the Mann-Whitney test, Spearman’s correlation coefficients and logistic regression models adjusted for age and BMI. A two-tailed P<0.05 was considered statistically significant.

Results: Of the 104 subjects with GD, 94% were female. Forty-nine subjects were included in the hyperthyroid group and 55 in the euthyroid group. No differences were observed between groups regarding age and BMI. Patients with higher levels of TRAb (OR=1.166; P=0.004), hs-CRP (OR=3.064; P=0.042), Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) (OR= 1.613; P=0.025) or insulinogenic index (IGI) (OR=2.933; P=0.046) had a higher risk of being hyperthyroid. In the overall population, TSH levels were positively correlated with folate (r=0.240; P=0.021), hepatic insulin sensitivity index (HISI) (r=0.217, P=0.046) and whole-body insulin sensitivity index (WBISI) (r=0.356, P=0.001). TSH levels were negatively correlated with TRAb (r=-0.461, P<0.001), HOMA-IR (r=-0.218, P=0.045) and IGI (r=-0.313, P=0.004). FT3 and FT4 levels were positively correlated with HOMA-IR (r=0.284, P=0.008 and r=0.261, P=0.016 respectively) and negatively correlated with HISI (r=-0.283; P=0.009 and r=-0.261, P=0.016 respectively) and WBISI (r=-0.233, P=0.032 and r=-0.260, P=0.016 respectively). Negative correlations were also found between FT3 levels and quantitative insulin sensitivity check index (QUICKI) (r=-0.281, P=0.009) and between FT4 levels and HDL-C (r=-0.198, P=0.046). In the hyperthyroid group, FT3 levels were positively correlated with levels of Lp(a) (r=0.367; P=0.020) and with HOMA-IR (r=0.384; P=0.017), and negatively correlated with QUICKI (r=-0.379; P=0.019) and HISI (r=-0.384; P=0.017). In the euthyroid group, TSH levels were positively correlated with WBISI values (r=0.291; P=0.047) and the levels of FT3 and vitamin B12 were negatively correlated (r=-0.358; P=0.01).

Conclusion: Our study shows a significant interrelationship between thyroid function, autoimmunity, insulin resistance, lipid profile, folate, vitamin B12 and low-grade inflammation in patients with GD.