Table 1: Variability in hematological parameters from two different brands of K3EDTA vacuum tubes.

Comprehensive results Hematological parameters (unit) Desirable Bias (%) Tube I Tube II Mean % difference ( value) RBC* (×106/L) 1.7 5.12 ± 0.41 [4.28–5.71] 5.08 ± 0.40 [4.31–5.64] 0.8 (<0.01) HCT* (%) 1.7 43.5 ± 3.1 [37.9–49.4] 42.9 ± 3.1 [36.9–49.1] 1.4 (< 0.01) HGB* (g/dL) 1.8 14.31 ± 1.13 [12.80–16.70] 14.29 ± 1.15 [12.70–16.70] 0.1 (0.56) MCV** (fL) 1.2 85.9 ± 6.7 [81.4–87.6] 85.6 ± 6.7 [81.1–87.0] 0.4 (< 0.01) MCHC** (pg) 1.4 28.6 ± 3.1 [26.6–29.3] 28.9 ± 3.2 [26.6–29.3] −1.0 (0.87) RDW** (%) 1.7 12.6 ± 1.1 [12.4–13.6] 12.6 ± 1.1 [12.4–13.7] 0.0 (0.94) WBC* (×103/L) 5.6 5.80 ± 1.08 [4.00–7.91] 5.88 ± 1.11 [3.94–8.01] −1.4 (0.15) LYMPHO* (×103/L) 7.4 1.90 ± 0.66 [0.81–3.33] 1.92 ± 0.70 [0.78–3.64] −1.0 (0.54) MONO* (×103/L) 13.2 0.35 ± 0.13 [0.17–0.69] 0.36 ± 0.12 [0.21–0.63] −2.9 (0.27) NEU* (×103/L) 9.0 3.35 ± 0.73 [2.38–4.93] 3.37 ± 0.72 [2.48–5.09] −0.6 (0.36) EOS* (×103/L) 19.8 0.15 ± 0.10 [0.02–0.36] 0.15 ± 0.10 [0.02–0.37] 0.0 (0.75) BASO* (×103/L) 15.4 0.041 ± 0.016 [0.020–0.070] 0.044 ± 0.020 [0.010–0.090] −7.3 (0.38) LUC* (×103/L) NA 0.154 ± 0.048 [0.070–0.260] 0.158 ± 0.054 [0.070–0.270] −2.6 (0.41) PLT* (×103/L) 5.9 298.3 ± 61.5 [228.0–431.0] 292.7 ± 56.3 [224.0–407.0] 1.9 (0.02) MPV* (fL) 2.3 8.45 ± 0.69 [7.30–9.80] 8.75 ± 0.84 [7.40–10.6] −3.6 (< 0.01) PDW** (%) 1.4 54.4 ± 6.6 [48.9–57.2] 51.8 ± 10.4 [48.8–58.6] 4.8 (< 0.01)

*Normal distribution; the values were mean ± standard deviation (range: minimum-maximum); value represents the significance by paired Student’s -test. **Nonnormal distribution; the values were median ± standard deviation (5th–95th percentiles); value represents the significance by Wilcoxon ranked-pairs test. The bold values are statistically significant (), and bold mean % differences represent clinically significant variations, when compared with desirable bias [15]. NA: not available [15]. Tube I: 4.5 mL Labor Import lot 20100505 (concentration of K3EDTA inside the tube is not made known by Shandong Weigao Group Medical Polymer, Weihai, China). Tube II: 1.2 mL S-Monovette lot 0092201 with 1.6 mg K3EDTA (Sarstedt, Nümbrecht, Germany).