Table 1.

Effect of 3 cooling cycles on clinical chemistry analytes of rat serum at 2 to 8 °C (refrigeration temperature)

		Cooling cycle 1 (24 h)		Cooling cycle 2 (48 h)		Cooling cycle 3 (72 h)
Analyte (unit)	Fresh sample	Mean ± 1 SD	% difference	Mean ± 1 SD	% difference	Mean ± 1 SD	% difference
Glucose (mg/dL)	152.0 ± 1.3	154.8 ± 0.7	1.8	158.8 ± 0.9	4.5	159.6 ± 1.3	5.0
Triglyceride (mg/dL)	139.8 ± 2.3	143.6 ± 2.2	2.7	151.9 ± 1.5	8.7	153.8 ± 2.5	10.0
Total cholesterol (mg/dL)	46.4 ± 0.7	47.2 ± 1.3	1.7	46.8 ± 0.7	0.9	46.4 ± 0.6	0.1
HDL cholesterol (mg/dL)	20.1 ± 0.5	20.2 ± 0.7	0.4	20.4 ± 0.3	1.4	19.7 ± 0.7	−2.2
AST (U/L)	127.7 ± 1.2	128.2 ± 1.7	0.5	130.5 ± 1.4	2.2	130.1 ± 0.9	1.9
ALT (U/L)	23.7 ± 0.6	24.3 ± 1.2	2.2	25.2 ± 0.9	6.2	24.4 ± 0.5	2.7
ALP (U/L)	119.3 ± 1.1	119.5 ± 0.5	0.1	119.6 ± 0.8	0.2	117.7 ± 0.9	−1.3
Total bilirubin (mg/dL)	0.16 ± 0.03	0.17 ± 0.01	3.1	0.16 ± 0.01	1.0	0.16 ± 0.01	−1.0
Total protein (g/dL)	5.8 ± 0.1	5.8 ± 0.1	−1.4	5.9 ± 0.1	1.1	5.9 ± 0.1	0.3
Albumin (g/dL)	3.7 ± 0.1	3.8 ± 0.1	1.8	3.8 ± 0.0	3.2	3.8 ± 0.0	2.3
Urea (mg/dL)	48.1 ± 1.4	47.3 ± 0.9	−1.6	48.1 ± 0.8	0.2	49.2 ± 0.9	2.4
Uric acid (mg/dL)	1.8 ± 0.1	1.9 ± 0.0	3.6	2.0 ± 0.1	6.4	2.0 ± 0.1	6.4
Creatine kinase (U/L)	1335.2 ± 16.5	1213.4 ± 53.6	−9.1	1223.1 ± 24.6	−8.4	1200.2 ± 12.9	−10.1
Calcium (mg/dL)	10.3 ± 0.2	10.2 ± 0.1	−1.1	10.6 ± 0.2	3.2	10.6 ± 0.1	3.1
Phosphorus (mg/dL)	6.5 ± 0.1	6.6 ± 0.1	2.8	6.2 ± 0.1	−3.9	6.2 ± 0.1	−3.4
Sodium (mmol/L)	138.9 ± 0.5	139.3 ± 0.4	0.3	139.2 ± 0.4	0.3	139.4 ± 0.3	0.4
Potassium (mmol/L)	3.9 ± 0.0	3.9 ± 0.0	0.4	3.9 ± 0.0	0.5	3.9 ± 0.0	0.3
Chloride (mmol/L)	102.2 ± 0.3	101.8 ± 0.4	−0.4	102.0 ± 0.2	−0.2	102.6 ± 0.5a	0.4

Data are given as mean ± 1 SD (n = 10), with the percentage difference relative to the value after immediate analysis

^aP < 0.05 as compared with value after immediate analysis of fresh sample.