EFFECTS OF STORAGE ON SERUM IONIZED CALCIUM AND PH VALUES IN CLINICALLY NORMAL DOGS

The stability of ionized calcium (Ca-I) concentration and pH in sera ( n = 14) stored at 23 or 4 C for 6, 9, 12, 24, 48, or 72 hours, or -10 C for 1, 3, 7, 14, or 30 days was evaluated. Also studied were the eff ects of oxygen exposure, cold handling, and feeding on Ca-I and pH val ues. Results indicated that serum Ca-I concentration was stable throug hout 72 hours of storage at 23 or 4 C, and for 7 days at -10 C. Serum Ca-I concentration significantly (P < 0.05) decreased by 14 days of st orage at -10 C. Serum pH was stable for 6 hours at 23 or 4 C, and for 24 hours at -10 C, but significantly (P < 0.05) increased by 9 hours o f storage at 23 or 4 C and by 3 days at -10 C. Exposure of the surface of the serum to air immediately before measurement had no effect on C a-I or pH values, but mixing serum with air resulted in significantly (P < 0.05) decreased Ca-I concentration and increased pH. Handling of blood on ice resulted in significantly (P < 0.05) higher serum pH, com pared with blood handled at 23 C, but serum Ca-I concentration was una ffected. Serum obtained at 2 hours after feeding did not have any sign ificant changes in Ca-I, total calcium, or pH values. It appears that if canine serum is obtained, handled, and stored anaerobically, Ca-I c oncentration can be accurately measured after 72 hours at 23 or 4 C, o r after 7 days at -10 C.