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 2

Renal water excretion during the water loading test in patients with adult dominant polycystic kidney disease (ADPKD), patients with non-ADPKD kidney disease (non-ADPKD), and healthy control subjects (controls).

Time		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-10.30 AM	Period 5; 10.30 AM-11.30 AM	Period 6; 11.30 AM-00.30 PM	Period 7; 00.30 PM-01.30 PM
CH20; (ml/min)	ADPKD; Non-ADPKD; Controls	(−0.52 ± 0.91); (−0.79 ± 0.81); (−0.83 ± 0.45)	(−0.52 ± 0.92); (−0.85 ± 0.61; (−0.97 ± 0.70	2.97 ± 2.42; 1.31 ± 1.50; 2.40 ± 2.71	5.80 ± 4.09; 4.71 ± 3.38; 6.89 ± 3.50	4.55 ± 2.25; 3.41 ± 1.86; 4.68 ± 2.27	1.77 ± 2.27; 1.59 ± 1.47; 1.22 ± 1.57	0.40 ± 1.71; 0.37 ± 1.34; (-0.14 ± 1.59
Comparison within groups		0.200
Comparison between groups		0.023
U-Osm; (mosmol/kg)	ADPKD; Non-ADPKD; Controls	485.6 ± 136.0; 568.8 ± 251.6; 538.3 ± 162.4	463.4 ± 149.1; 595.9 ± 187.3; 639.5 ± 209.4	199.7 ± 87.9; 287.3 ± 125.0; 235.4 ± 145.2	96.1 ± 25.7; 118.5 ± 43.8; 95.9 ± 41.7	111.0 ± 38.1; 126.1 ± 28.4; 113.7 ± 60.8	209.7 ± 106.6; 207.7 ± 92.9; 231.8 ± 143.5	313.2 ± 136.6; 307.8 ± 138.3; 403.7 ± 182.7
Comparison within groups		0.065
Comparison between groups		0.055
P-Osm; (mosmol/kg)	ADPKD; Non-ADPKD; Controls	X	292 ± 4; 293 ± 6; 292 ± 3	286 ± 5; 287 ± 5; 285 ± 4	286 ± 3; 287 ± 4; 286 ± 3	288 ± 4; 288 ± 5; 289 ± 4	288 ± 4; 289 ± 5; 290 ± 4	288 ± 4; 289 ± 5; 290 ± 4
Comparison within groups		X	0.075
Comparison between groups		X	0.758
U-AQP2 excretion rate (ng/min)	ADPKD; Non-ADPKD; Controls	0.70 [0.38; 1.20]; 0.75 [0.49; 1.58]; 0.69 [0.45; 1.01]	0.69 [0.39; 1.32]; 1.12 [0.66; 1.45]; 1.29 [0.50; 2.34]	0.04 [0.02; 0.10]; 0.11 [0.03; 0.17]; 0.03 [0.02; 0.13]	0.02 [0.01; 0.06]; 0.02 [0.01; 0.09]; 0.01 [0.00; 0.02]	0.02 [0.01; 0.03]; 0.02 [0.01; 0.05]; 0.01 [0.01; 0.03]	0.06 [0.03; 0.13]; 0.05 [0.03; 0.10]; 0.05 [0.03; 0.08]	0.15 [0.06; 0.27]; 0.15 [0.05; 0.20]; 0.23 [0.13; 0.48]
Kruskal-Wallis test		0.872	0.316	0.213	0.087	0.287	0.895	0.159
UO; (ml/min)	ADPKD; Non-ADPKD; Controls	1.57 ± 1.07; 1.13 ± 0.39; 1.16 ± 0.45	1.89 ± 1.61; 0.99 ± 0.36; 1.08 ± 0.63	6.50 ± 3.77; 4.47 ± 2.18; 5.55 ± 3.31	9.09 ± 4.89; 8.06 ± 3.63; 9.92 ± 4.13	7.33 ± 2.52; 6.09 ± 2.35; 7.35 ± 2.27	4.29 ± 2.55; 4.07 ± 1.42; 3.71 ± 1.43	2.80 ± 1.87; 2.89 ± 1.26; 2.35 ± 1.66
Comparison within groups		0.299
Comparison between groups		0.157

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. CH2O = free water clearance. U-AQP2 = urinary aquaporin-2, Osm = osmolality. UO = urine output.