Chronic Kidney Disease: Decreasing Serum Klotho Levels Predict Adverse Renal and Vascular Outcomes

Background and Objectives: Soluble alpha Klotho (s.Klotho) is an emerging marker for chronic kidney disease (CKD) prognosis. The objective was to study the association between s.Klotho and CKD-related decrease in glomerular filtration rate (GFR), bone and vascular damage. Method: A total of 118 patients with CKD stage 2-4 were enrolled and 107 patients continued in the study. Clinical and laboratory parameters were recorded at time of enrollment and 12 months. A double sandwich ELISA for s.Klotho was recorded in controls (n = 25) and patients' serum samples at 6 months (n = 107) and 12 months (n = 102). Primary endpoints like 40% or more fall in GFR, a requirement for renal replacement therapy (RRT), and death with different grades of s.Klotho deficiency were studied. Results: Of the 107 patients (80 male and 27 female), mean s.Klotho was 3.46 ng/mL (02.3-04.2). The GFR fall was significantly different (p value < 0.0001) in the different grades of s.Klotho deficiency with Grade 4 s.Klotho deficiency (0.1-2.99 ng/mL) having the maximum fall of GFR at 9.2 mL/min/1.73 m² (04.8-12.0) and minimum in Grade 2 (3-5.99 ng/mL) at 1.35 mL/min/1.73 m2 (03.0-02.75). The Ankle Brachial Pressure Index positively correlated with s.Klotho and the correlation coefficient was 0.536 (0.382-0.662) (p < 0.001). The carotid intimal medial thickness negatively correlated with s.Klotho and the correlation coefficient was -0.712 (95% CI: -0.797--0.601, p < 0.001). All five deaths had s.Klotho Grade 4 (severe) deficiency. The event-free survival rate was maximum (100%) in Grade 2 Klotho deficiency and lowest (55%) in Grade 4 s.Klotho deficiency. Conclusions: s.Klotho levels decreased significantly in patients with progressive kidney failure. s.Klotho levels significantly correlated with the presence of vascular disease. Death and need for RRT were significantly more in patients with severe s.Klotho deficiency.