The Circadian Rhythm of Copeptin, the C-Terminal Portion of Arginine Vasopressin

Table 1

Kinetic parameters of copeptin.

	AUC (24 h); pmol × h/L	pmol/L	h	pmol/L	h	pmol/L	Fluctuation index; %	Baseline copeptin; pmol/L
All subjects
Mean ± SEM	87.7 ± 7.5	2.3 ± 0.2	5.18 pm ± 1.1	5.9 ± 1.0	4.42 am ± 0.6 h	3.7 ± 0.3	120.5 ± 13.6	5.7 ± 0.7
Median (range)	87.8; (52.2–141.1)	2.2; (1.5–5.2)	6.30 pm; (5.30–12.00 pm)	4.5; (2.4–19.4)	5.00 am; (0.00–7:30 am)	3.7; (2.2–5.9)	113; (72.6–328.5)	4.8; (2.6–12.6)
Subpopulation A: baseline values ≥ median
Mean ± SEM	107.7 ± 8.4	2.8 ± 0.4	7.00 pm ± 0.7	8.7 ± 1.7	5.54 am ± 0.9	4.6 ± 0.4	163.4 ± 33.4	7.7 ± 0.8
Median (range)	93.0; (85.2–141.1)	2.5; (1.6–52)	7:00 pm; (4:00–10.5 pm)	7.4; (3.3–19.4)	6.48 am; (0.00–7.30 am)	3.9; (3.5–5.9)	144.9; (113.8–328.5)	7.3; (4.81–12.6)
Subpopulation B: baseline values < median
Mean ± SEM	67.7 ± 6.4	1.9 ± 0.1	3.48 pm ± 1.8	3.7 ± 0.4	3.30 am ± 0.9	2.8 ± 0.3	92.9 ± 6.1	3.4 ± 0.2
Median (range)	59.9; (52.2–100.0)	1.8; (1.5–3.0)	4.00 pm; (8.30 am–12.00pm)	3.2; (2.4–6.5)	3.00 am; (0.00–7:30 am)	2.5; (2.2–4.2)	88.9; (72.6–113.4)	3.3; (2.6–4.4)
-value^(2)	0.003	0.014	NS	0.043	NS	0.003	0.033	0.033

SEM = standard error of the mean; ⁽¹⁾measured for the period from 7.5 am to 7.5 am (24 hours); ⁽²⁾comparing the subgroups (e.g., baseline ≥ median versus baseline < median).