The Relationship Between Serum FGF23,Klotho And Calcium-phosphorus Metabolism In Patients With Chronic Kidney Disease

Objective: The purpose of the study was to evaluate the level of serum fibroblast growth factor-23(FGF23)and Klotho in chronic kidney diseases(CKD)patients without dialysis through an enzyme-linked immunosorbent assay(ELISA),and to explore the relationship between the both and calcium-phosphorus metabolic index.Methods: 90 CKD patients without dialysis were enrolled in the current study from January 1st 2016 to December 31 st 2016 in nephrology department of our hospital.Based on estimated glomerular filtration rate(eGFR),those patients were classified into CKD phase 1(CKD1,16 cases),CKD2(11 cases),CKD3(23 cases),CKD4(25 cases),and CKD5(15 cases).The basic clinical data of research objects was collected.The autobiochemistry analyzer was used to detect the serum calcium,serum phosphate,serum creatinine,serum albumin,24 h urinary electrolyte and so on;the immunochemical fluorescence method was used to detect intact parathyroid hormone(iPTH);the ELISA method was used to determine the concentration of FGF23 ? Klotho and 1,25-(OH)2VitD3 in serum;based on the obtained data,the corrected calcium,calcium-phosphorus product and fractional excretion of urine phosphate(FePi)were calculated;and eGFR was calculated based on the EPI formula.All the statistical analysis was performed with R language version 3.2.2 and a P value smaller than 0.05 was accepted as statistical significant.Results:1.On the whole,the level of FGF23 in CKD patients without dialysis went up asthe CKD progressed,and the result of variance analysis showed that,CKD staging had a statistically significant effect on the level of FGF23(P = 0.042).contrary to the variation trend of FGF23,the level of Klotho went down significantly as the CKD staging went up(P < 0.000).Among the various indexes that reflect the calcium-phosphorus metabolism,the level of PTH,serum phosphate,calcium-phosphorus product,FePi and other indexes markedly went up as CKD progressed,while the level of 1,25-(OH)2VitD3,serum calcium and 24 h urinary phosphorus and other indexes gradually went down as CKD progressed.2.The relevant analytic results showed that,the FGF23 in CKD patients without dialysis was negatively correlated with the level of Klotho(r=-0.22,P<0.05)and1,25-(OH)2VitD3(r=-0.20,P<0.05).While Klotho was significantly correlated with both calcium-phosphorus metabolic index and eGFR in our concern,wherein,Klotho was positively correlated with 1,25-(OH)2VitD3(r= 0.35,P<0.01),serum calcium(r= 0.25,P<0.05),24 h urinary phosphorus(r= 0.23,P<0.05)and eGFR(r= 0.51,P<0.01).While it was negatively correlated with PTH(r=-0.45,P<0.01),serum phosphate(r=-0.34,P<0.01),calcium-phosphorus product(r=-0.32,P<0.01)and FePi(r=-0.43,P<0.01).The whole data was corrected(the data in CKD2 stage was culled)and then secondarily analyzed,of which the result showed that,the correlation between FGF23 and each index had been elevated to some extent,meanwhile,in addition to the negative correlation with Klotho and 1,25-(OH)2VitD3,FGF23 was significantly negatively correlated with eGFR(r=-0.27,P<0.05)too.With the help of image illustration,from the perspective of holistic variation trend,the trend of change in FGF23 with the progression of CKD was consistent with that of PTH,serum phosphate,calcium-phosphorus product and FePi,and opposite to that of1,25-(OH)2VitD3,serum calcium,24 h urinary phosphate and eGFR.3.FGF23 and Klotho were divided into high and low level with the median as a standard,the difference in calcium-phosphorus metabolic index of kidney between different levels was compared.The result showed that,in the groups divided according to different level of FGF23,the difference between all the calcium-phosphorus metabolic indexes was not significant,while in the groupsdivided according to the level of Klotho,the difference between all the calcium-phosphorus metabolic indexes was significant.4.After eliminating the data of stage CKD1 patients,the differences in the FGF23 and Klotho levels of stage CKD1,stage 3,stage 4 and stage 5 patients who did not received hemodialysis were compared between different males and females.The results showed that stage CKD1,stage 3,stage 4 and stage 5 patients who did not received hemodialysis showed no significant difference in FGF23 level,while the Klotho level of stage CKD5 patients was obviously higher than that of female patients,showing a statistically significant difference.Conclusion:The level of FGF23 in CKD stages 1-5 patients without dialysis gradually goes up as CKD progresses,the level of Klotho gradually goes down as CKD progresses,the change in both was significantly negatively correlated with each other.But on the whole,the trend of change in FGF23 with the progression of CKD was consistent with that of PTH,serum phosphate,calcium-phosphorus product and FePi,and opposite to that of 1,25-(OH)2VitD3,serum calcium,24 h urinary phosphate and eGFR.The level of Klotho among CKD patients is positively correlated with1,25-(OH)2VitD3,serum calcium,24 h urinary phosphate and eGFR,and negatively correlated with PTH,serum phosphate,calcium-phosphorus product and FePi.