Table 3. Overview of laboratory values, and correlation with ΔT₅₀.

Laboratory values		A1.5	A1.25	C1.5	P-value#	Post-hoc (p-value, pairwise)*
						1	2	3
Phosphate (mmol/l)	Predialysis	1.38 [1.12–1.62]	1.49 [1.34–1.59]	1.47 [1.14–1.60]	0.36
	Postdialysis	0.63 [0.54–0.81]	0.57 [0.53–0.066]	0.54 [0.48–0.67]	0.14
	Delta	-0.84 [-0.96 - -0.64]	-0.98 [-1.05 - -0.80]	-0.94 [-1.03–0.72]	0.04	<0.01	0.005	0.14
	Correlation (r; p-value)	-0.69; 0.002	-0.51; 0.03	-0.34; 0.17
Ionized calcium (mmol/l)	Predialysis	1.14 [1.07–1.20]	1.14 [1.10–1.20]	1.14 [1.08–1.20]	0.64
	Postdialysis	1.26 [1.21–1.31]	1.13 [1.10–1.16]	1.10 [1.10–1.13]	<0.001	<0.001	<0.001	<0.001
	Delta	0.10 [0.07–0.14]	-0.01 [-0.05–0.01]	-0.04 [-0.06–0.02]	<0.001	<0.001	<0.001	0.04
	Correlation (r; p-value)	-0.15; 0.57	0.07; 0.80	-0.09; 0.75
Total calcium (mmol/l)	Predialysis	2.30 [2.14–2.42]	2.32 [2.11–2.40]	2.32 [2.14–2.41]	0.68
	Postdialysis	2.48 [2.35–2.54]	2.25 [2.21–2.32]	2.40 [2.29–2.45]	<0.001	<0.001	<0.001	<0.001
	Delta	0.16 [0.11–0.31]	-0.02 [-0.15–0.07]	0.08 [0.02–0.20]	<0.001	<0.001	<0.001	<0.001
	Correlation (r; p-value)	0.05; 0.86	0.18; 0.47	0.16; 0.52
Bicarbonate (mmol/l)	Predialysis	24.3 [22.7–25.9]	25.2 [23.4–26.8]	24.3 [23.0–26.1]	0.06
	Postdialysis	28.7 [27.4–30.4]	28.9 [28.0–30.8]	28.6 [27.0–30.0]	0.01	0.07	0.33	0.001
	Delta	5.0 [3.3–6.8]	5.3 [3.6–6.4]	4.5 [2.6–6.4]	<0.01	0.23	0.11	0.007
	Correlation (r; p-value)	-0.20; 0.44	0.02; 0.95	0.15; 0.54

Note: Data are expressed as median with 25^th and 75^th percentile, sorted by dialysate. All predialysis values are median from second and third session. Correlation is between the delta of each laboratory value and delta T₅₀, calculated with Spearman rho (showed as correlation; p-value). Total calcium is corrected for albumin by formula of Peyne.

^#P-values were calculated with Friedman test.

*Post hoc p-values were calculated with Wilcoxon Signed Rank test as pairwise comparisons and a p-value <0.017 was considered statistically significant based on Bonferroni correction. A1.5 = acetic-acid dialysate with 1.50mmol/l calcium, A1.25 = acetic-acid dialysate with 1.25mmol/l calcium, C1.5 = citric-acid dialysate with 1.50mmol/l calcium. 1 = A1.5 vs. A1.25; 2 = A1.5 vs. C1.5; 3 = A1.25 vs. C1.5.