Serum Ghrelin Levels in patients with Hashimoto's thyroiditis.

OBJECTIVE

Hypothyroidism is associated with changes in appetite and body weight. Ghrelin is an orexigenic peptide, and it stimulates appetite and increases food intake. However, the potential relationship between circulating ghrelin levels, hypothyroidism, and thyroid antibodies has not been adequately studied.

METHODS

Forty-seven patients with hypothyroidism due to Hashimoto's thyroiditis and 48 euthyroid subjects were enrolled in the study. Thyroid hormones and antibodies, insulin, glucose, ghrelin levels, and lipid parameters were measured in all the subjects.

RESULTS

Hypothyroid group showed significantly decreased serum levels of ghrelin and ghrelin=body mass index (BMI) compared to euthyroid group (31.9 +/- 21.5 pg/mL vs. 50.5 +/- 34.8 pg/mL, p < 0.001; and 1.24 +/- 0.93 vs. 2.12 +/- 1.53, p < 0.0001). In hypothyroid group, 6 months after treatment, ghrelin levels and ghrelin/BMI remained lower than euthyroid group (33.2 +/- 21.1 pg/mL vs. 50.5 +/- 34.8 pg/mL, p < 0.001; and 1.27 +/- 0.86 vs. 2.12 +/- 1.53, p < 0.0001). Ghrelin levels were decreased in hypothyroid patients with high thyroid peroxidase antibody (TPOAb) titre compared to hypothyroid patients with low TPOAb titre (19.1 +/- 23.1 pg/ mL vs. 35.3 +/- 17.4 pg/mL, p < 0.01). Ghrelin levels correlated positively with free triiodothyronine (FT3) and free thyroxine (FT4), and negatively with age, thyroglobulin antibody (TAb), TPOAb, total cholesterol (T-C), low-density lipoprotein cholesterol (LDL-C), very low-density lipoprotein cholesterol (VLDL-C), and triglycerides (TG) in hypothyroid group. In euthyroid group, circulating ghrelin levels correlated negatively with age, FT3, FT4, TG, and VLDL-C levels. No significant correlation was observed between ghrelin and homeostasis model assessment for insulin resistance (HOMA-IR) and between ghrelin and quantitative insulin sensitivity check index (QUICKI) in both groups. Regression analysis revealed that FT3 level is the most important predictor of ghrelin levels.

CONCLUSIONS

Thyroid hormones and antibodies seem to have a potential effect on serum ghrelin levels in patients with hypothyroidism.