Effects of storage time and temperature on ionized calcium concentration in bovine and ovine blood, plasma, and serum.

Stability of ionized calcium (Ca2+) concentration and pH values in bovine and ovine venous samples (n = 12 in each group) stored at 4 C for 3, 9, 24, and 48 hours (blood, plasma, and serum) or for 240 hours (plasma and serum), and at -20 C for 240 hours (plasma and serum), was studied. Storage of bovine and ovine blood, plasma, and serum samples at 4 C for up to 48 hours and of ovine serum samples at 4 C for up to 240 hours, despite appreciable pH changes, was associated with < 2.0% change in blood, plasma, and serum Ca2+ concentrations. Therefore, Ca2+ concentration in bovine and ovine venous blood, plasma, and serum samples stored up to 48 hours, and in ovine serum samples stored up to 240 hours, at 4 C is of diagnostic use.