Calcification of coronary arteries and aortic valve and circulating a-klotho levels in patients with chronic kidney disease

BACKGROUND: Evidence suggests that the anti-aging protein a-Klotho is a central modulator of mineral homeostasis. Circulating a-Klotho exerts endocrine activity and has been implicated in the process of vascular calcification, which is accelerated in patients with chronic kidney disease (CKD) and portends an unfavorable overall prognosis. However, the role of a-Klotho in this process remains unclear. The purpose of this study was to investigate the possible interaction between a-Klotho and the calcification of the aortic valve and coronary arteries in patients with CKD. METHODS: In this study we enrolled a total of 60 adult patients with CKD. Group 1 included 30 participants with CKD stage V and group 2 included 30 participants with CKD stage III. RESULTS: Participants in group 1 had lower levels of circulating a-Klotho compared to group 2 (390; 280–590 vs. 722; 501–897 pg/mL; P=0.001), were of younger age (55.5; 45–63 vs. 69; 62–74 years; P<0.001), had lower body mass index (25.6; 23.8–27.5 vs. 28.2; 25.7–31.1 kg/m(2); P=0.036), higher serum phosphate (4.75; 4–5.6 vs. 3.35; 2.9–3.8 mg/dL; P<0.001), higher calcium-phosphate product (41; 35.1–49.2 vs. 31.5; 28.6–35 mg(2)/dL(2); P<0.001), and higher parathyroid hormone (PTH) levels (28.4; 15–44.6 vs. 7.05; 4.3–10.2 pmol /L; P<0.001). CONCLUSIONS: No statistically significant difference was found between the two groups in terms of coronary arteries and aortic valve calcification. Calcitonin, PTH and phosphate were identified as predictors for circulating a-Klotho levels whereas, only hyperlipidemia was identified as predictor for coronary artery calcification. In conclusion, circulating a-Klotho is found to decrease with worsening CKD severity but no correlation was found between the levels of a-Klotho and severity of coronary arteries and aortic valve calcification.