Endocrine Abstracts

Aims: To examine whether Graves’ disease (GD) and Hashimoto thyroiditis (HT) are associated with insulin resistance (IR) and other cardiovascular risk factors. Patients and methods: We analyzed 479 patients with autoimmune thyroid disease, 354 (74%) with HT and 126 (26%) with GD, 94% woman, with a mean age of 46±16 years. The patients in both groups were properly treated in order to normalize TSH, FT₃ and FT₄ levels. We recorded thyroid function tests, BMI, IR markers comprising the homeostasis model assessment for insulin resistance, the quantitative insulin sensitivity check index, the hepatic insulin sensitivity index, the whole-body insulin sensitivity index, and the insulinogenic index. A 75-g OGTT was performed and measurements of plasma glucose, insulin, and C-peptide were obtained at 0 min (′), 30′, 60′, 90′ and 120′. We also recorded the levels of total cholesterol (TC), HDL, LDL-cholesterol, triglycerides (TG), apolipoprotein B (ApoB), ApoA1, lipoprotein (a), homocysteine, C-reactive protein, folic acid and vitamin B12 levels. Statistical analysis was performed with the Mann–Whitney U test and Spearman’s correlations tests. Results are expressed as mean±S.D. A two-tailed P≤0.05 was considered significant.

Results: We found that patients with HT had significantly higher levels of BMI (26.5±5.3 vs 24.8±4.7 kg/m², P=0.03); C-peptide at 30 min (7.3±2.8 vs 6.6±2.5 ng/ml; P=0.03); C-peptide at 60 min (10.5±4.2 vs 9.3±3.3 ng/ml; P<0.01). In patients with HT we also found significantly higher levels of LDL-cholesterol (124±31 vs 116±33 mg/dl; P<0.01), TG (116±70 vs 104±75 mg/dl; P=0.034), ApoB (97±23 vs 86±24 mg/dl; P<0.001), B12 vitamin (467±308 vs 372±174 pg/ml; P=0.02), anti-thyroglobulin antibody (141.7±179.0 vs 121.2±160.3 UI/ml, P=0.01). We found a negative correlation between TSH and TRAb levels (r=−0.180; P<0.001). In the whole group TSH positively correlated with TC (r=0.097; P=0.04) and ApoB (r=0.117; P=0.02). Conclusions: After treatment to normalize thyroid function, HT patients have a higher cardiovascular risk than GD patients, associated with overweight, subclinical inflammation and atherogenic lipid profile.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.