Table 1.

Characteristics of the population

Variables	Overall	Treatment duration
		Tertile 1 <2.5 yr	Tertile 2 2.5–10 yr	Tertile 3 >10 yr
n	217	68	70	79	P value
Age, yrs	51 [37–62]	38 [30–53]	45 [36–58]	60 [52–66]	<0.001
Male sex, n (%)	83 (38)	31 (46)	25 (36)	27 (34)	0.3
Hypertension, n (%)	56 (26)	20 (29)	17 (25)	19 (24)	0.7
BMI, kg/m2	26 [23–29]	26 [23–28]	26 [23–30]	26 [23–29]	0.6
Lithium treatment duration, yrs	5 [2–14]	1 [0.5–2]	4 [3–6]	18 [13–26]	<0.001
Sustained-release formulation	139 (65)	49 (74)	48 (71)	42 (53)	0.02
Lithium daily dose, mg/d	800 [575–1000]	1000 [688–1200]	800 [500–1000]	750 [500–888]	0.004
Serum lithemia, mmol/l	0.7 [0.6–0.9]	0.8 [0.6–0.9]	0.7 [0.6–0.8]	0.7 [0.6–0.9]	0.8
24-hour urine output, ml/d	1932 [1448–2835]	1662 [1227–2238]	1765 [1460–2443]	2516 [1794–3265]	<0.001
Polyuria >3 l/d	46 (21.4)	9 (13)	12 (17)	25 (32)	0.01
24-hour osmolar intake, mOsm/24 h	659 [516–847]	645 [506–887]	669 [507–837]	663 [551–829]	1
Fasting thirst score, on a 0–10 scale	5 [4–7]	6 [4–7]	5 [4–7]	5.00 [4.00, 7.00]	0.3
Fasting natremia, mmol/l	141 [140–142]	141 [140–141]	141 [140–142]	142 [141–144]	<0.001
Fasting Uosm, mOsm/kgH2O	578 [408–719]	689 [545–757]	621 [500–737]	406 [295–562]	<0.001
Maximal Uosm, mOsm/kgH2O	716 [547–853]	823 [706–898]	789 [636–870]	529 [385–683]	<0.001
Plasma copeptin, pmol/l	13 [8–23]	11 [8–16]	11 [7–14]	24 [14–42]	<0.001
Plasma vasopressin, pg/ml	5.8 [3.9–10.3]	5 [3.3–7.8]	5.7 [3.9–8.5]	7.7 [4.6–13.5]	0.005
mGFR, ml/min per 1.73 m2	78 [63–90]	88 [76–96]	84 [71–94]	63 [46–77]	<0.001
Renal microcysts, n (%)	N = 99				<0.001
0	49 (50)	19 (76)	23 (74)	7 (16)
1–10	30 (30)	6 (24)	8 (26)	16 (37)
11–50	10 (10)	0 (0)	0 (0)	10 (23)
>50	10 (10)	0 (0)	0 (0)	10 (23)

BMI, body mass index; mGFR, measured glomerular filtration rate; Q, quartile; Uosm, urine osmolality.

Data are expressed as median (Q1–Q3) or n (%). Comparisons were performed using Kruskal–Wallis test or χ² test.