Endocrine Abstracts

Introduction: Anomalies of glucose metabolism and insulin resistance are common in patients with hypothyroidism. Some studies suggests that euthyroid autoimmune thyroiditis (AIT) may also be associated with changes of glucose metabolism and insulin resistance. The role of thyroid hormones resistance in this context is still uncertain.

Aim: To evaluate the relationship between thyroid hormones resistance, insulin resistance and lipid profile in euthyroid patients with AIT.

Methods: We evaluated a sample of 40 patients with AIT. We assessed thyroid function tests and calculated the resistance to thyroid hormones [Parametric Thyroid Feedback Quantile-Based Index (PTFQI)]. Thyroid antibodies, lipid profile, high-sensitivity C-reactive protein, B12 vitamin, folic acid, anti-thyroid antibodies, and the insulin resistance indexes [HOMA-IR, HOMA-B, QUICKI (Quantitative Insulin Sensitivity Check Index), HISI (Hepatic Insulin Sensitivity Index), WBISI (Whole-Body ISI) and IGI (Insulinogenic Index)] were also evaluated. We divided patients in two groups: TSH <2.00 μUI/ml and TSH >2.00 μUI/ml. All patients had normal levels of TSH, FT3 and FT4. The statistical analysis was done with the Student’s t-test and Pearson correlation. We considered a two-tailed P-value of <0.05 significant.

Results: The mean age was 54.4 ± 13.6 years and 95 % were female. In the total group, we found a negative correlation between PTFQI and Lp(a) (r=-0.37; P=0.04). Patients with TSH >2.00 μUI/ml had significant higher levels of PTFQI (0.912±0.072 vs 0.701± 0.155; P≤ 0.001). Patients with TSH >2.00 μUI/ml had significant higher levels of A1c (5.73±0.35 vs 5.41±0.33 %; P=0.01). In the group with TSH <2.00 μUI/ml the following correlation were significant: PTFQI with LDL cholesterol (r=-0.44; P=0.04), QUICKI with triglycerides (r=0.48; P=0.02), QUICKI with B12 vitamin (r=0.69; P=0.001) and IGI with triglycerides (r=0.46; P=0.03). In the group with TSH >2.00 μUI/ml we found significative correlation between HOMA-B and ApoA1 (r=-0.86; P=0.01).

Conclusion: In euthyroid patients with AIT, we observed significant interrelationships between thyroid function, thyroid hormone resistance, lipid profile and insulin resistance, which may contribute to increased cardiovascular risk.