Serum α-Klotho Protein Can Be an independent Predictive Marker of Oxidative Stress (OS) and Declining Glomerular Function Rate in Chronic Kidney Disease (CKD) Patients

Introduction Chronic kidney disease (CKD) has been recognized as a global health problem. Progression of CKD to advanced stages is associated with a significant increase in the generation of reactive oxygen species (ROS). An antiaging protein, alpha-Klotho, is found expressed in the distal convoluted tubules of the kidney where, predominantly, it works to increase calcium absorption and potassium excretion in distal tubule via N-linked glycans. The association of serum alpha-Klotho with oxidative stress, inflammation, and fibrosis, as seen in CKD, highlights its importance for studying disease prognosis with declining glomerular function rate (GFR). Material and methods This was a case-control study consisting of 90 subjects. Fifty diagnosed cases of CKD attending the department of nephrology, SCB Medical College, Cuttack, Odisha, were included, and 40 age and sexmatched healthy volunteers were taken as control. Serum alpha-Klotho levels were measured using enzymelinked immunosorbent assay kits. Oxidative stress by estimating the total oxidant load by ferrous oxidationxylenol orange version 2 (FOX2) method and the total antioxidant capacity of serum by the ferric reducing ability of plasma (FRAP) method. Estimation of the estimated glomerular filtration rate (eGFR) was done using the Cockcroft and Gault equation. Results Serum alpha-Klotho (ng/ml) was found to be 2.591 0.98 in cases as compared to 0.24 +/- 0.09 in controls (p< 0.01). The serum total oxidant load (ng/ml) was 1.96 +/- 1.01 and 0.05 +/- 0.02 in cases and controls, respectively. Serum total antioxidant capacity (mu M) was measured as 281.80 +/- 78.0 in cases and 862.82 +/- 51.86 in controls. (p< 0.01). Serum Klotho has a negative correlation with eGFR in CKD patients (r = -0.065; p = 0.648). Conclusion The serum alpha-Klotho level was significantly higher in CKD patients than in healthy volunteers. Both serum alpha-Klotho and oxidative stress were negatively correlated with eGFR in CKD patients. Serum alpha-Klotho can be a suitable biomarker in CKD patients with declining GFR.