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14
Table 1. Profile of the participants in this study.
Patients
Healthy volunteers
(N = 57)
(N = 11)
Mean age (± SD)
68 (15)
Male ratio (%)
32 (56.1)
9 (81.8)
Hypertension (%)
24 (42.1)
0 (0)
Dyslipidaemia (%)
5 (8.8)
0 (0)
Diabetes mellitus (%)
10 (17.5)
0 (0)
Use of antithrombotic agents (%)
15 (26.3)
0 (0)
SD: standard deviation.
40 (7)
Figure legend
Figure 1. Change in serum potassium/sodium levels (mmol/L) (left) and rate of change (%) (right)
from the day of blood collection (T0d) to T14d after refrigeration storage (N = 5). Values shown
are means ± standard deviation (SD). Statistical significance was determined by using Dunnett’s
test. *P < 0.05 (versus serum potassium levels at T0d). **P < 0.05 (versus the rate of change from
T0d to T14d in serum sodium levels).
Figure 2. Relation between the increased serum potassium levels from the day of blood collection
(T0d) to T14d and the number of red blood cells (RBCs) in serum.
(A) Erythrocytes present in serum (×400)
(B) Correlation between the amount of change in serum potassium levels from T0d to T14d and
the number of RBC in serum on T0d (N = 7).
(C) Correlation between the number of erythrocytes in venous blood and serum on T0d (N = 36).
(D) Relationship between the number of RBCs and the potassium level after complete haemolysis.
Figure 3. Correlation between the amount of change in serum potassium levels from T0d to T14d
and the number of venous blood cells [(RBCs, white blood cells (WBCs), and platelets (PLTs)] at
T0d (N = 57). Statistical significance was determined using the Pearson correlation method. *P
< 0.05.
Figure 4. Differences in the increase in serum potassium levels due to centrifugation and type of
blood collection tube. The experiments were conducted using healthy volunteers, values shown
are means ± standard deviation (SD), and statistical significance was evaluated using Tukey’s test.
*P < 0.05.
(A) Rate of Change over time in serum potassium levels from the day of blood collection (T0d)
to T14d after different centrifugation conditions and refrigerated storage (N = 8).
(B) Representative image in blood collection after the replacement of serum with a saline solution
after centrifugation at 2330 × g for 7 min, 10min, 15min, and 1500 × g for 10 min (from T0d
to T14d). Arrows indicate haemoglobin pigment is visible.
(C) Increase in potassium levels in blood collection tubes at T14d after replacement of serum with
a saline solution and refrigerated storage (N = 5).
(D) Representative image in blood collection tubes, Insepac II, Neotube, and Venoject II after
centrifugation at 2330 × g for 7 min (T0d).
(E) Rate of Change in serum potassium levels from T0d to T14d after centrifugation under 2330
× g for 7 min in different types of blood collection tubes and refrigerated storage (N = 7).
Supplementary Figure 1.
Venous blood samples were obtained using Insepac II tubes. The serum was separated by
centrifugation using the method described above (2330 × g for 7 min), poured directly into a new
conical tube. To collect all RBCs remaining above the separator, 2mL of fresh saline was added
to their Insepac II tube, mixed by gently inverting, and then poured into the conical tube. The
above steps were repeated, and the sample’s total volume (almost 6mL) in conical tubes was
centrifuged at 1400 × g for 5 min. The supernatant was discarded, the pellet was suspended in 1
mL of saline, and the number of cells was counted using a Fuchs-Rosenthal counting chamber.
Supplementary Figure 2.
Blood was collected intravenously into a blood collection tube containing a separator and
centrifuged under the specified conditions (1710 × g for 10 min, and 2330 × g for 7 min, 10 min,
and 15 min). Because the RBCs in the serum that remain at the top of the separator must be
completely haemolyse, the serum layer was discarded, replaced with sterile water, mixed, and
allowed to stand for 6 h at room temperature. The upper layer was discarded, and then the saline
solution was added to the tubes. The upper layer was used as the sample. The samples were then
stored at 4°C for 14 days, and potassium levels were measured using TBA-120FR.
Supplementary Figure 3.
Rate of change (%) in serum potassium levels from the day of blood collection (T0d) to T14d
after refrigeration storage in patients on antithombotic drugs (N = 15) or not (N = 42).
Supplementary Figure 4.
Differences in the separation of serum and blood cell layers under different centrifugal conditions
(N = 5).
(A) Schematic image in this experiment. We centrifuged venous blood at 2330 × g for 7 min, and
15 min: the maximum blood cell layer diameter was (a, mm), and the minimum blood cell layer
diameter was (b, mm), and the serum layer diameter was (c, mm),
(B) Representative data in blood collection tube after centrifugation at 2330 × g for 7 min, and 15
min.
(C) The length of the serum layer was significantly greater when centrifuged at 2330 × g for 15
min than at 2330 × g for 7 min, and conversely, it was significantly less in the clot layer. Values
shown are means ± standard deviation (SD). Statistical significance was determined by using the
Student t test. *P < 0.05.
147
143
4.6
139
4.2
135
3.8
T0d T1d T3d T7d T14d
Rate of change from T0d (%)
5.4
Serum potassium levels (mmol/L)
Serum sodium levels (mmol/L)
Fig1
25
20
Na
15
10
**
-5
T0d T1d T3d T7d T14d
Fig2
Amount of change
in serum potassium levels
from T0d to T14d (mmol/L)
0.8
0.6
0.4
0.2
r = 0.014
10
20
30
40
50
Number of RBC in serum of T0d
(x106cells)
potassium levels after RBC hemolysis
(mmol/L)
Number of RBC in venous blood of T0d
(x1012/L)
r = 0.074
10
20
30
40
50
Number of RBC in serum of T0d
(x106cells)
0.8
0.7
0.6
0.5
0.4
0.3
0.2
r = 0.998
y= 0.0075x – 0.014
0.1
20
40
60
80 100 120
Number of RBC (x106/mL)
Fig3
RBC
r = 0.366*
0.4
0.8
1.2
PLT
WBC
14
600
r = 0.014
12
r = 0.044
500
(x109/L)
10
(x109/L)
Number of venous blood cells of T0d
(x1012/L)
400
300
200
100
0.4
0.8
1.2
0.4
0.8
1.2
Amount of change in serum potassium levels from T0d to T14d (mmol/L)
Fig4
30
20
15
* *
10
-5
T0d
T1d
T3d
1500 x g
2330 x g
10min 7min 10min 15min
T0d
T3d
T7d
T14d
T7d
T14d
Amount of change of potassium levels from
T0d to T14d after replacement with
a saline solution (mmol/L)
Rate of change in serum potassium levels
from T0d (%)
25
2330 x g
7min
2330 x g
10min
2330 x g
15min
1710 x g
15min
1500 x g
15min
1710 x g
10min
1500 x g
10 min
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
1500 x g 2330 x g 2330 x g 2330 x g
10 min 7 min 10 min 15 min
Fig4
T0d
40
Insepac II
Rate of change in serum potassium levels
from T0d (%)
35
Neotube
Venoject II
Insepac II
30
Neotube
25
Venoject II
20
15
10
-5
T0d
T1d
T3d
T7d
T14d
...
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