The Interplay Between Fibroblast Growth Factor-23 (Fgf-23) and Traditional Biomarkers of Chronic Kidney Disease - Mineral and Bone Disorder.

Introduction: Chronic kidney disease (CKD) is a global health challenge affecting 11-13% of the world's population. Chronic kidney disease - mineral and bone disorder (CKD-MBD) has been recognized as an important complication of CKD. There has been an increasing interest in fibroblast growth factor 23 (FGF-23), regarding its roles in the pathophysiology, diagnosis, and management of CKD-MBD but its relationship with other biomarkers of CKD-MBD has not been well investigated in sub-Saharan Africa, especially in Nigeria.

Method: This study aimed to assess the levels of FGF-23 in patients with kidney disease: Improving Global Outcome (KDIGO) CKD stages 3a to 5 and its relationship with traditional biomarkers of CKD-MBD. One hundred and thirty-eight (138) participants, 103 patients and 35 controls, completed the study. Serum intact parathyroid hormone (iPTH), FGF-23, and calcium among others were measured and a structured, interviewer-administered questionnaire was used to collect data. Data collected were analyzed using the Statistical Package for Social Sciences version 20 (SPSS 20).

Results: The mean serum levels of FGF-23 were different between patients (241.05 ± 3.40pg/ml) and the controls (133.66 ± 2.35pg/ml; p=0.009), and the same applied to the mean serum levels of iPTH for patients and controls (56.15 ± 43.48pg/ml vs 20.11 ± 5.57pg/ml, p = 0.009). The FGF-23 levels increased from stages 3 to 5; however, in stage 5 CKD, those on dialysis had lower iPTH and FGF-23 compared to those who were yet to commence dialysis. In the CKD arm, the calcium-phosphate product had a positive correlation with both FGF-23 and iPTH (r = 0.212; p = 0.01, and r = 0.195; p = 0.022, respectively). The prevalence of CKD-MBD increased as CKD progressed through stages 3 to 5 (72%, 90% and 100% respectively).

Conclusion: The prevalence of CKD-MBD was very high in this study, the rate progressively increased as GFR declined. FGF-23 showed a weak correlation with Ca x P product but did not correlate with calcium, phosphate, or iPTH.