and serum was harvested after allowing clotting for 4 h followed by centrifugation at 3000 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).