In comparing FGF21, GDF15, and NOS levels, it was found that the mean levels of FGF21 (1.24 ± 0.53 pg/mL vs. 0.95 ± 0.66 pg/mL, respectively) (p = 0.008) and NOS (1.72 ± 0.59 μg/mL vs. 1.43 ± 0.49 μg/mL, respectively) (p = 0.036) were significantly higher in the anemia group, whereas GDF15 levels showed similar results (see Table 2). Here, FGF21 is linked to anemia.