ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

Endocrine Abstracts (2019) 63 GP76 | DOI: 10.1530/endoabs.63.GP76

Cardiovascular risk factors, autoimmunity and insulin resistance in Graves disease

Cátia Tomás Ferreira1, Celestino Neves1,2,3, João Sérgio Neves1,2, Sofia Castro Oliveira1,2, Oksana Sokhatska1,4, Miguel Pereira2, Ana Oliveira2, José Luís Medina1, Luís Delgado1,4 & Davide Carvalho1,2,3

1Faculty of Medicine, University of Porto, Porto, Portugal; 2Department of Endocrinology, Diabetes and Metabolism, Centro Hospitalar Universitário de São João, Porto, Portugal; 3Institute for Research and Innovation in Health Sciences, University of Porto, Porto, Portugal; 4Service and Laboratory of Immunology, Centro Hospitalar Universitário de São João, Porto, Portugal.

Introduction: Graves’ disease is an autoimmune disease accounting for the majority of hyperthyroidism cases.

Aim: We aimed to assess the interrelationships between cardiovascular risk factors, autoimmunity, insulin resistance and treatment in Graves’ disease.

Material and methods: We measured free T3 (FT3), free T4 (FT4), TSH, thyrotropin receptor antibodies (TRAb), anti-thyroglobulin and anti-TPO antibodies, thyroid volume (each lobe’ volumes sum, given by the formula 0.479 × depth × wide × length), BMI, glucose, HbA1c, Homeostatic Model Assessment for Insulin Resistance (HOMA-IR), levels of total cholesterol (TC), HDL, LDL-cholesterol, triglycerides (TG), apolipoprotein B (ApoB), apoA1, lipoprotein(a) (Lp[a]), homocysteine, CRP (C-reactive protein), folic acid, B12 Vitamin in 85 patients with Graves’ disease (89.4% female, 52.8±13.4 years). Patients were divided in subgroups according to autoimmunity profile (positive TRAb (9.4%) or negative TRAb (81.2%)] and treatment [previously treated (80%) or in treatment with anti-thyroid drugs (20%)). Then, we divided the previously treated subgroup according to performed treatment [thyroidectomy (33.8%), I131 (13.2%) or anti-thyroid drugs (53%)]. Pearson correlation, t-test and Mann-Whitney test were performed for statistical analysis.

Results: Regarding TRAbs subgroups there was a positive correlation between Lp(a) and thyroid volume (r=0.4726, P=0.0228) in positive TRAb subgroup. A negative correlation between thyroid volume and FT3 (r=−0.4710, P=0.0065) was found in negative TRAb subgroup. Comparing with the previously treated subgroup, significantly higher thyroid volume (20.685±9.86 ml vs 15.43±1.398 ml, P=0.0480) and thyroglobulin (74.22±35.29 ng/ml vs 16.47±6.47 ng/ml, P=0.0315) and significantly lower TSH (0.85±0.15 UI/ml, vs 2.3±0.41 UI/ml, P=0.0139) were found in patients currently treated with antithyroid drugs. There was a positive correlation between HbA1c and thyroid volume (r=0.4290, P=0.0255), and between CRP and TC (r=0.4362, P=0.0375) in the previously treated subgroup. Regarding evaluation by performed treatment, significantly lower FT3 (2.395±0.37 pg/ml, IC95 (2.231–2.560), P=0.0319 vs 3.02±0.177 pg/ml, IC95 (2.67-3.38), P=0.032) was found in patients who performed thyroidectomy. In the thyroidectomy subgroup there was a positive correlation between FT3 and HOMA-IR (r=0.5734, P=0.0103). In patients without previous surgery or I131 treatment there was a positive correlation between age and thyroid volume (r=0.2972, P=0.0425), homocysteine and TRAb (r=0.7911, P=0.0341) and a negative correlation between thyroid volume and TRAb (r=−0.5275, P=0.0358).

Conclusion: In patients with Graves’ disease, we found significant interrelationships between thyroid volume and function, autoimmunity, lipid and glycaemic profiles. These associations may contribute to the cardiovascular risk in Graves’ disease.