Table 1. Tube equivalency study.

5 serum samples containing EDN were incubated with 5 different polypropylene tubes for 2hr at ambient temperature. ND: not determined.

Tube Type	EDN (ng/mL)
	Subject 1	Subject 2	Subject 3	Subject 4	Subject 5
Corning	38.4	48.7	33.3	58.3	105.2
Nalgene	38.4	51.7	34.5	50.1	105.1
Brand	35.9	50.1	35.1	57.8	101.6
Nunc	39.3	ND	35.6	60.0	98.6
Greiner	38.4	ND	36.6	52.5	97.7
Mean (CV)	38.2 (3.5%)	50.2 (1.5%)	35 (3.5%)	55.7 (7.6%)	101.6 (3.5%)