High serum soluble α-Klotho levels in patients with autosomal dominant polycystic kidney disease.

This study aims to determine fibroblast growth factor-23 and soluble α-Klotho levels in patients with autosomal dominant polycystic kidney disease. A total of 76 patients with autosomal dominant polycystic kidney disease and 32 healthy volunteers were included in the study. Serum fibroblast growth factor-23 and soluble α-Klotho levels were measured with ELISA kits. Parathyroid hormone, phosphate, calcium, creatinine, 25-hydroxyvitamin D3 levels, urinary protein to creatinine ratio and estimated glomerular filtration rate were also measured or calculated. Patients with autosomal dominant polycystic kidney disease had significantly higher serum parathyroid hormone (p<0.001), fibroblast growth factor-23 (p<0.001), soluble α-Klotho levels (p=0.001) and lower serum 25-hydroxyvitamin D3 levels (p<0.001) as compared with healthy volunteers. Serum fibroblast growth factor-23, soluble α-Klotho and 25-hydroxyvitamin D3 levels were similar in all five chronic kidney disease stages of autosomal dominant polycystic kidney disease (p>0.05). Fibroblast growth factor-23 (r=-0.251, p=0.034) and soluble α-Klotho levels (r=-0.251, p=0.034) were found to be negatively correlated with estimated glomerular filtration rate. This study shows increased fibroblast growth factor-23 levels in patients with autosomal dominant polycystic kidney disease which is in harmony with the general trend in patients with chronic kidney disease of other aetiologies, but, unlike them, also a significant increase in serum soluble α-Klotho levels in patients with autosomal dominant polycystic kidney disease suggesting an aberrant production or a decreased clearance of α-Klotho molecule. Considering the unique increases in erythropoietin levels due to erythropoietin production in renal cysts, we assume, patients with autosomal dominant polycystic kidney disease may potentially have different soluble α-Klotho production/clearance characteristics than the patients with other parenchymal renal diseases.