Soluble Klotho levels in diabetic nephropathy: relationship with arterial stiffness.

OBJECTIVE: In this cross-sectional study, we investigate the relationship between soluble Klotho (s-Klotho) levels, markers of bone mineral metabolism and arterial stiffness in 109 diabetic nephropathy patients (median age 61.00± 9.77 years) and 32 healthy controls (median age 49.23 ± 7.32 years). PATIENTS AND METHODS: Blood samples were collected to measure the levels of s- Klotho, and FGF23, serum creatinine, Calcium (Ca), Phosphorus (P), 25-hydroxyvitamin D3 (25hD) and parathyroid hormone (PTH). Pulse wave velocity (PWV) and blood pressure were also measured using a combined monitor. RESULTS: s-Klotho, FGF23 and PTH levels were significantly higher and 25hD was significantly lower in the patients than in controls (p < 0.001). Systolic blood pressure, pulse pressure and PWV were also significantly higher in the patients (p < 0.001). s-Klotho, FGF23 and 25hD levels significantly varied between sub-groups according to CKD stages, defined according to the CKD epidemiology collaboration equation. A strong positive correlation was found between s-Klotho and FGF23 (r = 0.768, p = 0.001) levels, but not with other bone mineral metabolism, blood pressure or arterial stiffness parameters. Creatinine levels significantly differed (p = 0.009) between three s-Klotho-level subgroups, with the high creatinine levels in the sub-group with the lowest s-Klotho levels and estimated glomerular filtration rate (eGFR). CONCLUSIONS: There was no correlation between eGFR and s-Klotho levels. Arterial stiffness increased in CKD but was not related to s- Klotho or FGF23 levels. Among all parameters, FGF23 levels had the greatest effect on s- Klotho levels. [ABSTRACT FROM AUTHOR]