Assessing the Relationship Between Serum Ghrelin Levels and Metabolic Parameters and Autoimmunity in Patients with Euthyroid Hashimoto's Thyroiditis

Abstract

Hashimoto's thyroiditis (HT) may affect metabolic parameters and increase predisposition to obesity. In this study, we aimed to assess the relationships among serum ghrelin concentrations, metabolic parameters, and thyroid autoimmunity in euthyroid HT patients. The study included 48 euthyroid HT patients and 41 age- and sex-matched healthy controls. We assessed serum ghrelin, free triiodothyronine (T3), free thyroxine (T4), thyroid-stimulating hormone (TSH), thyroid peroxidase antibody (anti-TPO), thyroglobulin antibody (anti-Tg), fasting blood glucose (FBG), insulin, lipid levels, and homeostasis model assessment insulin resistance (HOMA-IR) in all subjects. Sex distribution, mean age, and body mass index (BMI) were similar in HT patients and controls (female/male, 42/6 vs. 33/8, 46.8 ± 14.7 vs. 45 ± 12.5 years, 28.5 ± 6.1 vs. 28.4 ± 4.9 kg/m2, respectively; P>.05 for all). The mean waist circumference (WC) of the HT group was significantly higher than that of the control group (100.6 ± 14.6 vs. 93.2 ± 13.2 cm, P = .015). While FBG, low-density lipoprotein cholesterol (LDL-C), and triglyceride levels in the HT group were significantly higher than in the control group, insulin levels and HOMA-IR were similar. Ghrelin levels were lower in HT patients compared to controls (416.9 ± 224.4 and 689.9 ± 191.6 pg/mL, respectively; P<.001). Ghrelin levels were similar in patients with low and high anti-TPO titers. Negative correlations were observed between ghrelin levels and BMI, WC, and anti-TPO levels. Regression analysis revealed that HT was the most important predictor of ghrelin levels. Euthyroid HT is associated with a decrease in plasma ghrelin levels. Altered body fat distribution and increased anti-TPO levels do not seem to be directly involved in lower ghrelin levels in euthyroid HT patients.