Circulating α-Klotho is Related to Plasma Aldosterone and Its Follow-Up Change Predicts CKD Progression

BACKGROUND/AIMS: We aimed to determine if soluble α-klotho level was an indicator of chronic kidney disease (CKD) progression and whether α-klotho interacted with aldosterone during the course of further renal damage. METHODS: 112 adults with stages 1-5 CKD were enrolled into our cohort study. All of the patients were followed up for 6 years (from January 2010 to December 2015). Serum soluble α-klotho and aldosterone were measured at baseline and at 1.5-years follow-up. The primary outcome was the initiation of renal replacement therapy (RRT) and the secondary outcome was the occurrence of cardio-cerebrovascular events. Long-term progression to RRT and cardio-cerebrovascular events in patients was analyzed with a risk-adjusted Cox proportional hazards regression model. Adjustment included age, gender, eGFR, mean arterial pressure, 24-h protein excretion and the change in α-klotho level from baseline at 1.5-years follow-up. RESULTS: Baseline circulating α-klotho levels were positively associated with baseline estimated glomerular filtration rate (eGFR; r = 0.224, p = 0.017), but not age, calcium, phosphate, or parathyroid hormone levels. The change in α-klotho level from baseline at 1.5-years follow-up (p = 0.002) was independently associated with renal replace treatment (RRT) initiation after adjustment for age, gender, eGFR, mean arterial pressure, and 24-h protein excretion in Cox regression analysis. Aldosterone levels were positively associated with CKD stage, and were inversely correlated with circulating α-klotho levels. CONCLUSION: The change in concentration of soluble α-klotho during the 1.5-years follow-up was an indicator of CKD progression. Renal damage associated with a reduction of α-klotho may involve the upregulation of plasma aldosterone. Future studies are needed to validate our findings, and to investigate the underlying mechanism by which α-klotho and aldosterone may cause renal damage.