Table 3.

Stability of various soluble activation markers in unprocessed blood stored at different temperatures.^a

Biomarker	Unprocessed blood stored at room temperature (20–25 °C)				Unprocessed blood stored in the refrigerator (4–8 °C)
	Intercept	Coefficient	SE	p > |z|	Intercept	Coefficient	SE	p > |z|
sIL-2Rα (pg/mL)
Serum	943	0.5476	1.434	0.703	955	−0.2086	1.059	0.844
EDTA plasma	603	2.9243	2.104	0.165	611	−1.0638	2.216	0.631
Heparin plasma	715	−0.0292	0.835	0.972	715	−0.2133	1.837	0.908
sTNF-RII (ng/mL)
Serum	2.35	0.0051	0.005	0.261	2.38	−0.0063	0.006	0.330
EDTA plasma	1.76	0.0030	0.006	0.584	1.71	0.0031	0.005	0.560
Heparin plasma	1.87	−0.0023	0.005	0.611	1.78	0.0035	0.002	0.032
β2-microglobulin (mg/L)
Serum	1.29	0.0015	0.002	0.472	1.31	0.0008	0.003	0.779
EDTA plasma	1.04	0.0032	0.002	0.077	1.05	−0.0022	0.002	0.338
Heparin plasma	1.14	−0.0029	0.002	0.210	1.19	−0.0033	0.003	0.296
Neopterin (nmol/L)
Serum	5.79	0.0143	0.008	0.065	5.78	0.0039	0.004	0.275
EDTA plasma	6.18	0.0710	0.007	<0.0001	6.10	0.0132	0.013	0.307
Heparin plasma	5.12	−0.0057	0.012	0.637	5.05	−0.0013	0.008	0.861

^aThe intercept is the mean concentration at baseline; coefficient is the predicted change in concentration each hour for 24 h; SE is the standard error of the coefficient; and p > |z| is the calculated p value using the generalized estimating equation. p values ≤0.05 are considered statistically significant and are bolded.