A Comparison of Urine Dilution Ability between Adult Dominant Polycystic Kidney Disease, Other Chronic Kidney Diseases, and Healthy Control Subjects: A Case-Control Study

Table 3

Kidney tubular function during urine dilution test in patients with adult dominant polycystic kidney disease (ADPKD), patients with non-ADPKD kidney disease (non-ADPKD), and healthy control subjects (controls).

		Baseline; Period 1; 07.30 AM-07.30 AM	Baseline; Period 2; 07.30 AM-08.30 AM	Period 3; 08.30 AM-09.30 AM	Period 4; 09.30 AM-10.30AM	Period 5; 10.30 AM-11.30 AM	Period 6; 11.30 AM-00.30 PM	Period 7; 00.30 PM-01.30 PM
CCr (ml/min)	ADPKD; Non-ADPKD; Controls	107.9 ± 49.5; 85.3 ± 49.0; 128.1 ± 33.1	111.8 ± 52.3; 83.3 ± 45.1; 137.1 ± 35.8	121.5 ± 44.5; 97.0 ± 48.4; 141.7 ± 30.2	120.0 ± 44.2; 99.1 ± 47.1; 135.9 ± 27.0	107.8 ± 42.2; 89.4 ± 44.5; 127.3 ± 23.6	105.3 ± 43.3; 93.5 ± 47.9; 123.7 ± 32.7	106.0 ± 48.4; 96.8 ± 50.8; 133.0 ± 33.5
Comparison within groups		0.204
Comparison between groups		0.018
FENa; (%)	ADPKD; Non-ADPKD; Controls	0.79 ± 0.33; 1.08 ± 0.59; 0.50 ± 0.17	0.92 ± 0.60; 1.09 ± 0.72; 0.51 ± 0.24	1.56 ± 0.93; 1.83 ± 1.14; 0.90 ± 0.36	1.58 ± 0.82; 2.34 ± 1.71; 0.90 ± 0.41	1.42 ± 0.77; 1.84 ± 1.30; 0.88 ± 0.36	1.31 ± 0.62; 1.50 ± 1.03; 0.96 ± 0.29	1.31 ± 0.58; 1.55 ± 0.98; 1.00 ± 0.35
Comparison within groups		0.099
Comparison between groups		0.002
Alb excretion rate (mg/min)	ADPKD; Non-ADPKD; Controls	0.017 [0.001; 0.063]; 0.088 [0.032; 0.280]; 0.003 [0.002; 0.007]	0.012 [0.005; 0.057]; 0.066 [0.036; 0.470]; 0.007 [0.002; 0.018]	0.002 [0.000; 0.007]; 0.012 [0.002; 0.041]; 0.000 [0.000; 0.001]	0.001 [0.000; 0.003]; 0.002 [0.001; 0.010]; 0.000 [0.000; 0.000]	0.000 [0.000; 0.002]; 0.003 [0.000; 0.015]; 0.000 [0.000; 0.000]	0.001 [0.000; 0.004]; 0.005 [0.001; 0.025]; 0.000 [0.000; 0.001]	0.002 [0.001; 0.006]; 0.013 [0.002; 0.046]; 0.001 [0.000; 0.002]
Kruskal-Wallis test		<0.001	<0.001	<0.001	<0.001	<0.001	<0.001	0.002
U-ENaC excretion rate (ng/min)	ADPKD; Non-ADPKD; Controls	0.57 [0.42; 0.99]; 0.74 [0.58; 1.35; 0.80 [0.56; 1.15]	0.49 [0.43; 1.1]; 0.84 [0.67; 1.56]; 0.89 [0.60; 2.9]	0.03 [0.02; 0.08]; 0.13 [0.03; 0.20]; 0.02 [0.01; 0.09]	0.01 [0.00; 0.05]; 0.02 [0.01; 0.08]; 0.01 [0.00; 0.01]	0.01 [0.01; 0.02]; 0.02 [0.01; 0.04]; 0.01 [0.01; 0.03]	0.05 [0.02; 0.10]; 0.05 [0.03; 011]; 0.05 [0.03; 0.08]	0.11 [0.07; 0.20]; 0.10 [0.05; 0.19]; 0.20 [0.07; 0.36]
Kruskal-Wallis test		0.590	0.074	0.143	0.195	0.086	0.954	0.292

An oral water load of 20 ml/body weight was given immediately after period 2. Urine was collected in seven periods. Period 1 (24 hours): from 07.30 AM the day before arrival to the laboratory to 07.30 AM on the examination day. Period 2 (one hour): 07.30–08.30 AM. Period 3 one hour): 08.30–09.30 AM. Period 4 (one hour): 09.30–11.30 AM. Period 5 (one hour): 10.30–11.30 AM. Period 6 (one hour): 11.30–00.30 PM. Period 7 (on hour): 00.30–01.30 PM. 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 ∗ between ADPKD or Non-ADPKD patients and controls. # between ADPKD and Non-ADPKD patients. C_Cr = creatinine clearance. Alb = albumin. FE_Na = fractional excretion of sodium. U-ENaC = urinary epithelial sodium channel.