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Table 1 Baseline characteristics of the 169 PD patients in our study cohort

From: Factors affecting the relationship between ionized and corrected calcium levels in peritoneal dialysis patients: a retrospective cross-sectional study

Variable No. of Missing Value (%) Whole patients iCa/cCa ratio P value
< 47.0% 47.0 to < 49.0% ≥49.0%
Number 0 (0) 169 56 (33%) 54 (32%) 59 (35%)  
Male [%] 0 (0) 124 (73%) 40 (71%) 37 (69%) 47 (80%) 0.38
Age [y] 0 (0) 62 ± 13 63 ± 13 61 ± 14 61 ± 14 0.56
PD duration [months] 0 (0) 24 (11–50) 32 (12–74) 24 (12–44) 18 (9–40) 0.04
BMI [kg/m2] 0 (0) 23.7 ± 4.3 22.9 ± 4.1 23.8 ± 4.8 24.5 ± 4.0 0.14
Underlying disease       0.89
 CGN [%] 0 (0) 50 (30%) 16 (28%) 18 (33%) 16 (27%)  
 Diabetes [%] 0 (0) 61 (36%) 21 (38%) 21 (39%) 19 (32%)  
 Nephrosclerosis [%] 0 (0) 29 (17%) 11 (20%) 6 (11%) 12 (20%)  
 PCKD [%] 0 (0) 6 (4%) 1 (2%) 2 (4%) 3 (5%)  
 Others or unknown [%] 0 (0) 23 (14%) 7 (13%) 7 (13%) 9 (15%)  
Comorbidity
 CVD [%] 0 (0) 52 (31%) 19 (34%) 22 (41%) 11 (19%) 0.03
Residual renal function
 Urine volume [ml] 25 (14.8) 700 (300–1500) 500 (200–1080) 600 (190–1420) 900 (540–1730) 0.01
 Weekly renal Kt/V 49 (29.0) 0.46 (0.14–0.83) 0.25 (0.09–0.61) 0.43 (0.12–0.73) 0.66 (0.40–1.00) < 0.01
PD solution
 Dialysate Volume [L] 0 (0) 5.8 ± 1.8 6.3 ± 1.5 5.7 ± 1.9 5.5 ± 1.9 0.045
Medication
 Cinacalcet [%] 0 (0) 47 (28%) 23 (41%) 13 (24%) 11 (19%) 0.02
 Vitamin D [%] 0 (0) 91 (54%) 27 (48%) 29 (54%) 35 (59%) 0.49
 Ca-containing P binder [%] 0 (0) 47 (28%) 23 (41%) 10 (19%) 14 (24%) 0.02
 Ca-free P binder [%] 0 (0) 86 (51%) 26 (46%) 37 (69%) 23 (39%) < 0.01
Laboratory data
 pH 0 (0) 7.34 ± 0.04 7.366 ± 0.033 7.339 ± 0.005 7.328 ± 0.005 < 0.01
 Bicarbonate [mmol/L] 0 (0) 24.8 ± 2.5 25.3 ± 2.5 24.7 ± 2.3 24.3 ± 2.5 0.08
 Hemoglobin [g/dL] 2 (1.2) 11.2 ± 1.3 10.8 ± 1.5 11.1 ± 1.1 11.6 ± 1.2 < 0.01
 Creatinine [mg/dL] 0 (0) 10.4 ± 3.2 10.7 ± 2.8 11.1 ± 3.6 9.6 ± 2.9 0.04
 Albumin [g/dL] 0 (0) 3.3 ± 0.5 2.9 ± 0.4 3.4 ± 0.5 3.5 ± 0.3 < 0.01
 Phosphorus [mg/dL] 0 (0) 5.4 ± 1.3 5.4 ± 1.2 5.5 ± 1.6 5.4 ± 1.0 0.84
 Total Ca [mg/dL] 0 (0) 8.7 ± 0.7 8.5 ± 0.7 8.6 ± 0.6 8.9 ± 0.6 < 0.01
 cCa [mg/dL] 0 (0) 9.4 ± 0.7 9.6 ± 0.8 9.3 ± 0.6 9.3 ± 0.6 0.02
 iCa [mmol/L] 0 (0) 1.13 ± 0.09 1.09 ± 0.09 1.12 ± 0.07 1.18 ± 0.07 < 0.01
aiCa [mg/dL] 0 (0) 4.5 ± 0.4 4.6 ± 0.3 4.4 ± 0.4 4.4 ± 0.4 < 0.01
 iCa/cCa ratio [%] 0 (0) 48.2 ± 2.5 45.4 ± 1.5 48.1 ± 0.6 50.7 ± 1.4 < 0.01
 Intact PTH [pg/dL] 0 (0) 176 (103–255) 180 (111–269) 177 (121–264) 151 (85–233) 0.54
 CRP [mg/dL] 0 (0) 0.12 (0.05–0.36) 0.22 (0.05–0.43) 0.12 (0.05–0.32) 0.08 (0.04–0.23) 0.06
  1. Abbreviations: PD peritoneal dialysis, BMI body mass index, CGN chronic glomerulonephritis, PCKD polycystic kidney disease, CVD cardiovascular disease, Ca calcium, cCa corrected calcium, iCa ionized calcium, PTH parathyroid hormone, CRP C-reactive protein
  2. aiCa levels represented as mg/dL; these are the same data as above in mmol/L.
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