Background  Hyperthyroidism can affect the metabolic process of bile acid. However, the specific causes of this effect have not yet been fully elucidated and the results are inconsistent across studies.

  Objective  To explore the correlation between bile acid metabolites and thyroid function in patients with Graves disease.

  Methods  From November 2018 to November 2019, 39 Graves disease patients and 39 normal control subjects were enrolled after matching for age, sex and body mass index from Beijing Chaoyang Hospital, and the biological and clinical data were collected. Of the 39 Graves disease patients, there were 13 males and 26 females with average age of (43.87 ± 4.46) years. Differences of baseline clinical and biochemical measurements as well as levels of bile acids between Graves disease patients and healthy controls were evaluated using the independent sample t-test for normally distributed variables or the Mann-Whitney test for skewed distributed variables. Spearman correlation coefficients were calculated between serum bile acids and thyroid function parameters.

  Results  Significant increases in serum levels of taurocholic acid (TCA), tauro-ursodeoxycholic acid (TUDCA), tauro-α-muricholic acid (TαMCA), and significant decrease in serum levels of glycodeoxycholic acid (GDCA), chenodeoxycholic acid (CDCA), lithocholic acid (LCA), hyodeoxycholic acid (HDCA), deoxycholic acid (DCA), taurodeoxycholic acid (TDCA) were observed in Graves disease patients compared to healthy controls (all P ＜0.05). There was no statistically significant difference in other bile acids between the two groups(P >0.05). Spearman correlation analysis found that the level of FT3 in the case group was negatively correlated with DCA (r=-0.379, P=0.039), HDCA (r=-0.486, P=0.006) and CDCA (r=-0.361, P=0.046), and was positively correlated with TUDCA (r=0.340, P=0.042). And FT4 level was negatively correlated with CDCA (r=-0.408, P=0.023), DCA (r=-0.427, P=0.019), GDCA (r=-0.371, P=0.048) and HDCA (r=-0.447, P=0.012).

  Conclusion  Compared to the healthy patient, the concentration of different bile acids is remarkably changed in Graves patients’ serum, which are correlated with FT3 and FT4.