[Undercarboxylated osteocalcin (Glu-OC) bone metabolism and vascular calcification in hemodialyzed patients]

Abstract

Osteocalcin (OC) is witamino-K dependent calcium-binding protein comprising three gamma carboxy glutamic acid residues (Gla) which determines a strong bond with hydroxyapatite. In vitamin K deficiency and/or increased bone resorption undercarboxylated osteocalcin (Glu-OC) appears in the blood. The aim of this study was to evaluate the level of Glu-OC and markers of bone metabolism and their impact on coronary artery calcification in patients with end-stage renal failure treated with repeated hemodialysis. The study included 68 patients (29 women and 39 men) aged 60.3 +/- 12.3 years hemodialysis period 24.5 +/- 4.8 months. Control group consisted of 35 healthy volunteers comparable in terms of age and gender. CACS was evaluated based on multislice spiral computed tomography (MSCT). Measurement of carboxylated osteocalcin (Gla-OC) and Glu-OC, bone alkaline phosphatase (bALP), tartrate-resistant acid phosphatase (TRAP5) were assessed by ELISA and iPTH by Nichols method. Present study demonstrated that the Gla-OC and Glu-OC in hemodialysis patients were significantly higher than the control group 116.37 +/- 70.01 ng/ml and 93.72 +/- 112.63 ng/ml versus 19.51 +/- 3.78 ng/ml and 4.88 +/- 2.63 ng/ ml; p <0.001. Glu-OC level correlated significantly with iPTH, bALP, TRAP5 (p <0.001) and CaSc (p <0.014).

Conclusions: 1. The results indicate a significant correlation between Glu-OC and assessed markers of bone metabolism. 2. Research has indicated a link between bone metabolism and the degree of calcification in the coronary arteries.