Biochemical values stability in serum and plasma of renal diseased patients
The stability of five parameters in serum and plasma after prolonged storage was studied by determining the effects of storage temperature and time on the laboratory results of samples obtained from renal diseased patients. Serum and plasma were separated from clot and red cells and analysed in duplicates immediately to obtain the baseline fresh value (zero hour value). The remaining serum and plasma were stored at 40C ± 20C and 320C ± 20C for 4, 8, 12, 16, 20, 24, 30, 36, 42, 48, 72, 96 and 120 hours, and then assayed in duplicates. Statistically significant changes from the zero hour mean value were determined using ANOVA. Instability (P<0.05) was observed at 320C for sodium and potassium ions after 96 hours, chloride after 72 hours, creatinine after 42hours and urea after 24 hours. All parameters in serum and plasma stored at 40C (refrigerated) were stable within 5 days. Proper storage temperatures and time must therefore be considered for these analytes if measurement does not to take place immediately after specimen collection.