Urine concentration ability is reduced to the same degree in adult dominant polycystic kidney disease compared with other chronic kidney diseases in the same CKD-stage and lower THAN in healthy control subjects - a CASE control study

Table 3 Fractional excretion of sodium, (FE_Na), urine excretion of a fraction of epithelial sodium channel (u-ENaC), urine albumin excretion rate (u-Alb), creatinine clearance (C_Creatinine) during a water deprivation test in patients with adult dominant polycystic kidney disease (ADPKD), patients with non-ADPKD kidney disease (Non-ADPKD), and healthy control subjects (Controls). Urine was collected in four periods. Period 1 (twelve hours): from 0730 PM the day before arrival to the laboratory to 0730 AM on the examination day. Period 2 (one hour): 0730 to 0830 AM. Period 3 (two hours): 0830–1030 AM. Period 4 (two hours): 1030–1230 AM

	Period 1 07.30 PM- 07.30 AM	Period 2 07.30 AM- 08.30 AM	Period 3 08.30 AM–10.30 AM	Period 4 10.30 AM- 12.30 PM
FE_Na (%)
ADPKD	1.1 ± 0.5*	0.9 ± 0.5*	1.2 ± 0.7*	1.2 ± 0.7*
Non-ADPKD	1.3 ± 0.8*	1.1 ± 0.7*	1.5 ± 1.0*	1.4 ± 1.0*
Controls	0.6 ± 0.3	0.5 ± 0.2	0.7 ± 0.3	0.8 ± 0.3
Comparison within groups	0.910
Comparison between groups	0.014
U-ENaC (ng/ml)
ADPKD	0.6 ± 0.3*	0.6 ± 0.3*	0.4 ± 0.2*	0.4 ± 0.2*
Non-ADPKD	0.6 ± 0.3	0.9 ± 0.5	0.5 ± 0.3*	0.5 ± 0.2*
Controls	0.9 ± 0.4	1.2 ± 0.5	0.8 ± 0.5	0.8 ± 0.3
Comparison within groups	0.394
Comparison between groups	0.003
U-ENaC (ng/min)
ADPKD	0.3 [0.1;0.9]*	0.5 [0.2;1.0]*	0.3 [0.2;0.6]*	0.3 [0.2;0.5]*
Non-ADPKD	0.3 [0.2;0.6]*	0.9[0.5;1.2]*	0.3 [0.1;0.6]*	0.4 [0.3;1.0]*
Controls	0.8 [0.4;2.0]	1.7[1.2;2.9]	1.2 [0.5;2.1]	0.9 [0.7;1.9]
Krusal-Wallis H	0.023	0.001	0.011	< 0.001
U-Alb (mg/min)
ADPKD	0.01 [0.01;0.02]*	0.02 [0.01;0.05]#	0.01 [0.00;0.03]	0.01 [0.01;0.03]#
Non-ADPKD	0.04 [0.01;0.17]*	0.08 [0.02;0.44]*	0.02 [0.01;0.49]*	0.4 [0.14;0.22]*
Controls	0.01 [0.00;0.01]	0.01 [0.01;0.02)	0.01 [000;0.02]	0.01 [0.00;0.02]
Kruskal-Wallis test	0.003	0.001	0.032	0.001
C_Creatinine (ml/min)
ADPKD	104.0 ± 43.3	109 ± 41	108 ± 36*	106 ± 40*
Non-ADPKD	101.3 ± 57.9	93 ± 50*	101 ± 50*	94 ± 48*
Controls	127.7 ± 27.7	133 ± 28	131 ± 24	132 ± 23
Comparison within groups	0.809
Comparison between groups	0.040

A General Linear Model with Greenhouse-Geisser correction was used for comparison within and between the three groups. Values represent mean ± SD or median with 25 and 75% percentiles in brackets * = p < 0.05 between ADPKD or non-ADPKD- patients and healthy controls. # = p < 0.05 between ADPKD and non-ADPKD- patients

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