In addition, there was an association of serum KRT1 levels with FT4 in all subjects and the AITD group (r = 0.164, p = 0.041; r = 0.161, p = 0.046, Fig 4E and 4F, respectively), while there was no association of serum KRT1 levels with FT4 in the GD or HT groups (r = 0.126, p = 0.168; r = 0.221, p = 0.223, Fig 4G and 4H, respectively). Here, KRT1 is linked to hematocrit.