Notably, the positive correlation between serum FGF21 levels and TACS in HD patients was also obtained in our study, which was contrary to the result that FGF21 inhibited vascular calcification in vitro and animal experiments [32,33], highlighting the need for further studies to explore the exact mechanism of FGF21 elevation on vascular calcification in CKD patients. The gene discussed is FGF21; the disease is chronic kidney disease.