. 2018 Oct 21;7(1):42–52. doi: 10.1111/andr.12554

Table 3.

Measured T levels after addition of TU to different blood collection tubes to yield a concentration of 0, 300, and 600 ng/mL from healthy men^a

	Incubation time (min) – temperature	TU 0 ng/mL		TU 300 ng/mL		TU 600 ng/mL
	Incubation time (min) – temperature	T (ng/dL)	% difference vs. Plain^b	T (ng/dL)	% difference vs. no TU added	T (ng/dL)	% difference vs. no TU added
Experiment 1
Plain	30 – 4 °C	349.5		412.0	+17.9	455.5	+30.3
Plain	30 – RT	353.0		505.0	+43.1	814.0	+130.6
NaF (15 mg/mL)	30 – 4 °C	271.0	−22.5	269.5	−0.6	336.5	+24.2
NaF (15 mg/mL)	30 – RT	259.0	−26.6	301.5	+16.4	360.0	+39.0
P‐800	30 – 4 °C	323.5	−7.4	384.0	+18.7	374.5	+15.8
P‐800	30 – RT	329.5	−6.7	467.0	+41.7	643.0	+95.1
Experiment 2
Plain	30 – 4 °C	437.5		624.5	+42.7	541.0	+23.7
	60 – 4 °C	420.5		741.5	+76.3	794.0	+88.8
	60 – RT	407.5		984.0	+141.5	1515.0	+271.8
K₂EDTA (1.8 mg/mL)	30 – 4 °C	443.5	+1.4	534.5	+20.5	539.5	+21.6
	60 – 4 °C	454.5	+8.1	521.5	+14.7	669.5	+47.3
	60 – RT	481.0	+18.0	1105.0	+129.7	1765.0	+266.9
NaF (1.5 mg/mL) + Na₂EDTA (3 mg/mL)	30 – 4 °C	414.0	−5.4	443.0	+7.0	482.5	+16.5
	60 – 4 °C	411.0	−2.3	497.0	+20.9	654.5	+59.2
	60 – RT	447.5	+9.8	705.0	+57.5	1235.0	+176.0
NaF (5 mg/mL) + K₂Oxalate (4 mg/mL)	30 – 4 °C	391.5	−10.5	387.5	−1.0	438.0	+11.9
	60 – 4 °C	380.5	−9.5	435.0	+14.3	494.0	+29.8
	60 – RT	399.5	−2.0	717.0	+79.5	1085.0	+171.6
P800	30 – 4 °C	435.5	−0.5	492.5	+13.1	515.0	+18.3
	60 – 4 °C	476.0	+13.2	491.5	+3.3	582.0	+22.3
	60 – RT	428.0	+5.0	860.0	+100.9	1380.0	+222.4

Note that for the ex vivo spiking studies, 2 mL blood was added to each tube. Thus, the tubes were not filled to their nominal draw volume, so the final NaF concentration does not match the concentration present in the clinical setting (see Table 2). The results from duplicate tubes were averaged.

% difference vs. plain—relative difference vs. plain tube kept at same conditions.