Correlation of FGF-23 With Biochemical Markers and Bone Density in Chronic Kidney Disease-Bone Mineral Density Disorder.

Aim The purpose of this study was to determine the relationship between biochemical markers such as serum calcium (Ca), phosphorus (P), intact parathyroid hormone (iPTH), 25(OH) vitamin D, and fibroblast growth factor 23 (FGF23) in our study group, as well as to correlate dual-energy X-ray absorptiometry (DEXA) findings with these biochemical markers. Methodology  An eligible group of 50 chronic hemodialysis (HD) patients, age 18 and older, who have undergone HD two times a week for at least six months participated in this retrospective cross-sectional study. We compared serum FGF23, intact parathyroid hormone (iPTH), 25(OH) vitamin D, calcium, phosphorus, and dual-energy X-ray absorptiometry scan showing bone mineral density disorder (BMD) around the femoral neck, distal radius, and lumbar spine. Human FGF23 Enzyme Linked Immuno Sorbent Assay (ELISA) Kit PicoKine® (Catalog # EK0759; Boster Biological Technology, Pleasanton, CA) was used in the optimum moisture content (OMC) lab to measure FGF23 levels. For the analysis of associations with various studied variables, the levels of FGF23 were split into two groups, which were high (group 1, FGF23 50 to 500 pg/ml), that is, up to 10 times the normal levels and extremely high (group 2, FGF23 > 500 pg/ml) FGF23 levels. All the tests were conducted for routine examination where the data obtained was analyzed in this research project.  Results The mean age of patients was 39.18 ±12.84 years, of whom 35 (70%) were males and 15 (30%) were females. For the entire cohort, serum PTH levels were consistently high, and vitamin D levels were low. FGF23 levels were high in the whole cohort. The average iPTH concentration was 304.20 ± 113.18 pg/ml, while the average 25(OH) vitamin D concentration was 19.68±7.49 ng/ml. The mean FGF23 levels were 1877.36±1378.67 pg./ml. The mean calcium value was 8.23±1.05 mg /dl and the mean phosphate of 6.56±2.28 mg /dl. In the whole cohort, FGF23 showed a negative correlation with vitamin D and a positive correlation with PTH, but not statistically significant. Extremely high FGF23 levels were associated with lower bone density compared to high FGF23 values. Considering that in the whole cohort of patients, only nine had high FGF-23 and the rest of 41 patients had extremely high FGF23, we could not ascertain differences in PTH, calcium, phosphorus, and 25(OH) vitamin D levels between the two groups. The average length of time on dialysis was eight months, and there was no link between FGF-23 levels and the length of time on dialysis. Conclusion Bone demineralization and biochemical abnormalities are a hallmark in chronic kidney disease (CKD) patients. Abnormalities in serum phosphate, parathyroid hormone, calcium, and 25(OH) vitamin D play critical roles in the development of BMD in CKD patients. With the discovery of FGF-23 as a biomarker that is increased early in CKD patients, new questions arise about the effects and actions of FGF-23 in controlling bone demineralization and other biochemical markers. Our study found no statistically significant correlation to suggest an effect of FGF-23 on these parameters. But the findings need to be looked at more in prospective, controlled research, especially to find out if therapies that successfully target FGF-23 can make a big difference in how people with CKD feel about their health.