Objective: To evaluate the interrelationships between thyroid function, insulin resistance, lipid profile, homocysteine, C-reactive protein (CRP), folic acid, and vitamin B12 levels, in Graves disease (GD).
Methods: We recorded thyroid function tests, BMI, insulin resistance markers, lipid profile, homocysteine, CRP, folic acid, and vitamin B12 levels, in 104 subjects with GD in the first cycle of treatment with methimazole, 94% of whom were female. The subjects were classified into two groups: 49 patients were included in the hyperthyroid group (fT3 >3.71 pg/ml and/or fT4 >1.48 ng/dl, and TSH <0.35 UI/ml) and 55 in the euthyroid group. Statistical analysis was performed with MannWhitney U test, logistic regression, and Pearsons correlations test. Results are expressed as median and percentiles (2575). A two-tailed P value <0.05 was considered significant.
Results: Significantly higher levels of TRAb (UI/ml) were found in the hyperthyroid patients (3.2 (1.512.1) vs 1.1 (0.52.0), P<0.001). The levels of folate (ng/ml) and WBISI were significantly lower in the hyperthyroid group (5.1 (3.66.5) vs 6.9 (5.19.4), P=0.001 and 4.39 (2.496.15) vs 5.50 (4.087.79), P=0.015). Across all patients, TSH levels were positively correlated with folate (r=0.240, P=0.021), HISI (r=0.217, P=0.046), and WBISI (r=0.356, P=0.001) and 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). The levels of fT3 and fT4 were positively correlated with HOMA-IR (r=0.284, P=0.008 and r=0.261, P=0.016) and negatively correlated with HISI (r=−0.283, P=0.009 and r=−0.261, P=0.016) and WBISI (r=−0.233, P=0.032 and r=−0.260, P=0.016). Negative correlations were also found between fT3 levels and QUICKI (r=−0.281, P=0.009) and between fT4 levels and HDL-C (r=−0.198, P=0.046). In the hyperthyroid group we found significant correlations between fT3 and Lp(a) (r=0.367, P<0.05). In the euthyroid group we found negative correlations between fT3 and vitamin B12 (r=−0.358, P<0.01).
Conclusion: We found that patients with higher levels of TRAb and insulin resistance had a higher risk of being hyperthyroid in Graves disease. On the other hand, patients with higher folate levels had a lower risk of being hyperthyroid.
16 - 20 May 2015
European Society of Endocrinology