Background: Thyroid hormones modulate the lipoprotein and glucose metabolisms. In hyperthyroidism, insulin resistance is a frequent finding.
Aim: To assess interrelationships between thyroid function, autoimmunity, lipid profile, glucose metabolism and other cardiovascular risk factors in patients with Graves disease.
Methods: We recorded free T3 (FT3), free T4 (FT4), TSH, TSH receptor antibodies (TRAB), parameters of the lipid profile, glucose metabolism [including insulin resistance marker Homeostasis Model Assessment for Insulin Resistance (HOMA-IR)], C reactive protein (CRP) and homocysteine in 126 patients with Graves disease in the first cycle of treatment with methimazole (93% females, mean age 44.8±15.2 years). Patients were divided in subgroups according to: TRAB (positive (n=57) or negative (n=69)) and thyroid function (normal (n=74), subclinical (n=29) or clinical hyperthyroidism (n=22)). Spearman correlations, T-tests and MannWhitney tests were performed for statistical analysis.
Results: Comparing TRAB- and TRAB+ groups, significantly lower apolipoprotein B (80.3(73.287.4) vs 89.7(83.595.8)mg/dl, P=0.047) and TSH (0.180(0.0021.080) vs 1.020(0.2352.055]μUI/ml, P<0.001) were found in the TRAB+ group. Comparing with the normal thyroid function group, patients in the clinical hyperthyroid group presented significantly lower apolipoprotein B (70.9(57.284.6) vs 89.7(83.795.8)mg/dl, P=0.007) and higher fasting glucose (96.0(83.0109.0) vs 86.4(83.889.0)mg/dl, P=0.019), insulin (10.4(6.215.8) vs 7.5(4.89.7)μUI/ml, P=0.021), HOMA-IR (2.09(1.294.53) vs 1.55(0.952.13), P=0.023) and CRP (0.57(0.200.93) vs 0.20(0.070.38)mg/l, P=0.005). No significant differences were found between the subclinical hyperthyroid group and the remaining groups. There was a negative correlation between TSH and TRAB (r=−0.386, P<0.001). Apolipoprotein B was positively correlated with TSH (r=0.236, P=0.016), and negatively with TRAB (r=−0.211, P=0.030). Both FT3 and FT4 were positively correlated with fasting insulin (r=0.268, P=0.008 and r=0.226, P=0.025, respectively) and HOMA-IR (r=0.258, P=0.010 and r=0.259, P=0.010, respectively). FT4 was also positively correlated with fasting glucose (r=0.269, P=0.008).
Conclusion: In patients with Graves disease, the interrelationships between thyroid function, autoimmunity, insulin resistance and lipid profile may contribute to the increased cardiovascular risk.
20 May 2017 - 23 May 2017