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Abstract: PO2504

C-Terminal and Intact FGF-23 in Kidney Transplant Recipients and Their Associations with Kidney Transplant Loss and Mortality

Session Information

Category: Transplantation

  • 1902 Transplantation: Clinical

Authors

  • Chu, Chang, Charité - Universitätsmedizin Berlin, Campus Mitte, Berlin, Germany
  • Zeng, Shufei, Charité - Universitätsmedizin Berlin, Campus Mitte, Berlin, Germany
  • Xiong, Yingquan, Institute of Nutritional Science, University of Potsdam, Potsdam, Germany
  • Hasan, Ahmed A., Institute of Nutritional Science, University of Potsdam, Potsdam, Germany
  • Krämer, Bernhard K., Fifth Department of Medicine (Nephrology/ Endocrinology/ Rheumatology), University Medical Centre Mannheim, University of Heidelberg, Germany, Mannheim, Germany
  • Hocher, Berthold, Fifth Department of Medicine (Nephrology/ Endocrinology/ Rheumatology), University Medical Centre Mannheim, University of Heidelberg, Germany, Mannheim, Germany
Background

Increased fibroblast growth factor 23 (FGF23) is a risk factor for mortality, cardiovascular disease, and progression of chronic kidney disease. Limited data exist comparing the association of either c-terminal FGF23 (cFGF23) or intact FGF23 (iFGF23) in kidney transplant at recipients (KTPs) with graft loss and all-cause mortality.

Methods

We conducted a prospective observational cohort study in 562 stable kidney transplant recipients. Patients were followed for graft loss and all-cause mortality for a follow-up of 48 months.

Results

During a median follow-up of 48 months, 94 patients had adverse outcome (graft loss or died). Both cFGF23 and iFGF23 concentrations were significantly higher in patients who had adverse outcome than those without adverse outcome (24.59 [11.43-87.82] versus 10.67 [5.99-22.73] pg/ml; p<0.0001 and 45.24 [18.63-159.0] versus 29.04 [15.23-60.65] pg/ml; p=0.002 for cFGF23 and iFGF23, respectively). cFGF23 and iFGF23 measurements correlated well (rho=0.54, p <0.0001). ROC analysis of cFGF23 and iFGF23 yielded AUC of 0.69 (p <0.0001) and 0.61 (p =0.002) for prediction of the composite endpoint, respectively. Cox regression analyses adjusted for confounding factors, showed that cFGF23 (HR for one unit increase of log transformed cFGF23: 1.35; 95% CI, 1.03-1.77; p=0.028) but not iFGF23 (HR for one unit increase of log transformed iFGF23: 1.03; 95% CI, 0.81-1.31; p=0.827) was associated with the composite endpoint (Figure 1).

Conclusion

Elevated cFGF23 levels at baseline are independently associated with an increased risk all-cause mortality or graft loss. iFGF23 measurements were not independently associated with the study endpoint. The cFGF23 ELISA might detect bioactive FGF23 fragments that are not detected by the iFGF23 ELISA.