was harvested af ter allowing clotting for 4 h followed by
centrifugation at 30 0 0 g for 10 min at 4 1C. Plasma and
serum samples were stored in 2 mL micro tubes with
screw cap (Sarstedt, Nümbrecht, Germany) at 18 1C until
further analysis. Additional serum samples were stored at
80 1C for analysis of parathyroid hormone (PTH).