Soluble average Klotho level as a prognostic marker for acute kidney injury outcomes: a 90-day follow-up study

Klotho is highly expressed in the kidney and confers pleiotropic kidney protective effects. This study aimed to assess the soluble average Klotho level and its relationship to renal function and outcomes in participants with acute kidney injury (AKI). We recruited 102 participants with AKI and 30 healthy controls (HCs). For patients with AKI, serum soluble (sKlotho) levels upon admission to and discharge from hospital were measured to assess the relationship between sKlotho level and kidney function. Individuals with AKI were followed up for 90 days to determine the association between their average sKlotho level and short-term AKI outcomes. The baseline sKlotho level in individuals with AKI at admission was significantly lower than that in HCs. For individuals with AKI, the sKlotho level was significantly lower in stage 3 than in stage 1 or 2. The sKlotho level was restored along with renal function improvement at discharge. During follow-up, a lower average, but not baseline, sKlotho level, or average sKlotho/creatinine ration predicted more AKI clinical outcomes. The sKlotho level decreased significantly with kidney injury and represented severity. The average sKlotho level inversely correlated with detrimental kidney outcomes and may have potential diagnostic and predictive roles in AKI. <b>The diagnostic and prognostic performances of sKlotho for patients with acute kidney injury</b> Acute kidney injury (AKI) is one of the most common critical illnesses, with higher incidence, poorer prognosis and limited effective therapeutics in clinical practice. Screning and identifying possible biomarkers is critical for AKI management. Klotho is a novel identified protein that exerts renal protection and received much more attention in nephrology nowadays. Available evidence demonstrated that Klotho is increasingly considered as a biomarker and therapeutic target for chronic kidney disease. However, the sKlotho level in acute kidney injury (AKI) patients is controversial and whether a reduced level of sKlotho can predict outcomes in AKI patients is unclear. In this current study. we aimed to ascertain if sKlotho could be a diagnostic or prognostic biomarker in this population. We recruited 102 participants with AKI and 30 healthy controls (HCs). For patients with AKI, serum sKlotho levels upon admission to and discharge from hospital were measured to assess the relationship between the sKlotho level and kidney function. Individuals with AKI were prospectively followed up for 90 days to determine the association between their average sKlotho level and short-term AKI outcomes. Interestingly, we found that sKlotho value was significantly decreased and an alteration in the sKlotho level ran parallel to changes in kidney function in AKI patients. Furthermore, we observed that, a lower average, but not baseline, sKlotho level predicted more adverse AKI clinical outcomes (no recovery or death). Collectively, our findings indicated a possible diagnostic and prognostic performances of sKlotho in AKI patients. We believe that our study provided implications into the sKlotho’s clinical significance for AKI patients.