Table 5 Change of serum sodium and potassium (all patients and hyponatremia patients)

All patients (N)

76

153

301

Serum Na⁺ concentration (mmol/L)

Baseline

137.7 ± 4.4

–

136.7 ± 5.1

–

136.9 ± 4.8

–

–

–

–

4–8 h

136.2 ± 5.2

− 1.4 ± 3.1

137.7 ± 5.9

1.0 ± 3.6

138.2 ± 5.8

1.3 ± 3.8

< 0.001

< 0.001

0.408

Day 1

137.6 ± 4.6

− 0.1 ± 2.8

138.8 ± 5.4

2.0 ± 3.4

140.3 ± 4.9

3.4 ± 3.4

< 0.001

< 0.001

< 0.001

Day 4

137.4 ± 5.1

− 0.3 ± 3.14

138.3 ± 5.1

1.6 ± 3.0

139.6 ± 4.7

2.7 ± 3.9

< 0.001

< 0.001

0.002

Day 7

137.0 ± 5.1

− 0.7 ± 3.4

138.2 ± 5.1

1.4 ± 3.3

139.0 ± 4.6

2.1 ± 4.0

< 0.001

< 0.001

0.075

Serum K⁺ concentration (mmol/L)

Baseline

3.9 ± 0.5

–

4.1 ± 0.6

–

4.0 ± 0.5

–

–

–

–

Day 4

4.0 ± 0.7

0.1 ± 0.5

4.2 ± 0.4

0.1 ± 0.5

4.2 ± 0.7

0.1 ± 0.7

0.752

0.845

0.494

Day 7

4.0 ± 0.5

0.1 ± 0.5

4.2 ± 0.5

0.1 ± 0.5

4.2 ± 0.5

0.2 ± 0.6

0.885

0.390

0.199

Hyponatremia patients (Na⁺ baseline< 135 mmol/L) (N)

17

41

85

Serum Na⁺ concentration (mmol/L)

Baseline

131.3 ± 3.1

–

130.2 ± 4.5

–

130.9 ± 3.7

–

–

–

–

4–8 h

129.4 ± 4.6

− 1.9 ± 3.7

131.1 ± 5.7

1.0 ± 3.9

132.7 ± 6.2

1.8 ± 4.3

0.019

< 0.001

0.260

Day 1

132.6 ± 4.9

1.2 ± 3.7

133.5 ± 6.0

3.3 ± 3.8

135.6 ± 5.1

4.7 ± 3.7

0.061

< 0.001

0.057

Day 4

131.2 ± 5.0

− 0.1 ± 4.6

133.2 ± 5.9

3.0 ± 3.2

135.4 ± 5.1

4.5 ± 4.6

0.013

< 0.001

0.063

Day 7

130.3 ± 4.7

− 1.0 ± 4.1

132.8 ± 5.2

2.6 ± 3.2

134.9 ± 4.9

4.0 ± 5.1

0.005

< 0.001

0.144