Five days serum glucose stability at room-temperature in centrifuged fast-clotting serum tubes and the comparability with glucose in heparin-plasma and plasma containing citrate-stabilizer

Figures & data

Table 1. Median glucose concentration (1st-3rd quartile) at T₀ according to tube type.

	LiH	CAT serum fast separator	FC-mix	SST
Median glucose (mmol/L)	5.23 (5.00–6.00)	5.24 (4.88–5.76)	5.47 (5.06–6.07)	5.09 (4.76–5.68)
Bias (mmol/L)		0.01	0.24	−0.14
Bias %		0.2	4.7	−2.6
p Value		<0.01	<0.01	<0.01

LiH: lithium-heparin; CAT serum fast separator: fast-clotting serum; FC-mix: NaF–EDTA–citrate; SST: serum separator tube.

n = 30.

Figure 1. Relative difference of glucose concentration (%) vs. T₀ after storage of centrifuged samples at 20–22 °C according to tube type. Mean difference between baseline glucose and glucose after storage is shown with red data points (90% confidence interval). Individual differences are shown as grey data points. The red dashed lines present the maximal allowable bias, the grey dashed lines present the maximal allowable total error. (A) Fast-clotting serum, (B) NaF–EDTA–citrate plasma and (C) serum.

Table 2. Median glucose concentration (1st–3rd quartile) at 20–22 °C according to tube type and storage time.

		Glucose, mmol/L
Storage	Tube type	0 h	24 h	48 h	72 h	96 h	120 h	p Value
20–22 °C, n = 30	CAT serum fast separator	5.24 (4.88–5.76)	5.21 (4.90–5.76)	5.25 (4.88–5.85)	5.23 (4.88–5.94)	5.16 (4.90–5.86)	5.21 (4.85–5.91)	.034
	FC-mix	5.47 (5.06–6.07)	5.42* (5.06–6.03)	5.47 (5.03–6.14)	5.54 (5.05–6.22)	5.49 (5.05–6.16)	5.46 (5.03–6.14)	.008
	SST	5.09 (4.76–5.68)	5.07 (4.77–5.74)	5.09 (4.77–5.79)	5.11* (4.79–5.84)	5.07 (4.74–5.80)	5.11 (4.71–5.82)	.011

FC-mix: NaF–EDTA–citrate; SST: serum separator tube.

* Statistically significant difference to T₀ after pairwise comparison adjusted by Bonferroni’s correction for multiple tests.