Table 2.

Results from full linear mixed-effects models (equation (4)) for individual isomers of OH-Phe (n = 154).

	1-OH-Phe		(2+3)-OH-Phe		4-OH-Phe		9-OH-Phe
Parameters	Estimate (SE)	p-value	Estimate (SE)	p-value	Estimate (SE)	p-value	Estimate (SE)	p-value
Fixed effects
Intercept [ln(ng/L)]	5.83 (0.800)	<0.0001	7.11 (0.734)	<0.0001	3.40 (0.694)	0.0002	6.42 (0.573)	<0.0001
CREATININE [ln(g/L)]	0.637 (0.101)	<0.0001	0.522 (0.086)	<0.0001	0.597 (0.127)	<0.0001	0.662 (0.109)	<0.0001
TIME		0.4		0.1		0.3		0.05
postshift	−0.169 (0.322)		−0.346 (0.274)		−0.049 (0.412)		−0.021 (0.356)
bedtime	−0.340 (0.240)		−0.424 (0.204)		−0.490 (0.308)		−0.627 (0.267)
morning	0 (ref)		0 (ref)		0 (ref)		0 (ref)
DAY		0.006		0.001		0.2		0.04
day 3	−0.131 (0.240)		0.384 (0.204)		−0.371 (0.311)		−0.517 (0.270)
day 2	0.565 (0.223)		0.720 (0.190)		0.218 (0.289)		0.155 (0.251)
day 1	0 (ref)		0 (ref)		0 (ref)		0 (ref)
U-PHE [ln(ng/L)]	0.200 (0.062)	<0.0001	0.191 (0.052)	<0.0001	0.261 (0.079)	<0.0001	0.408 (0.069)	<0.0001
U-PHE×TIME		0.02		<0.0001		0.4		0.06
U-Phe×postshift	0.139 (0.083)		0.258 (0.070)		0.114 (0.106)		0.073 (0.092)
U-Phe×bedtime	0.202 (0.073)		0.272 (0.062)		0.129 (0.094)		0.192 (0.081)
U-Phe×morning	0 (ref)		0 (ref)		0 (ref)		0 (ref)
U-PHE×DAY		0.01		0.01		0.1		0.06
U-Phe×day 3	0.073 (0.066)		−0.052 (0.056)		0.145 (0.085)		0.139 (0.074)
U-Phe×day 2	−0.110 (0.061)		−0.152 (0.052)		−0.005 (0.078)		−0.017 (0.068)
U-Phe×day 1	0 (ref)		0 (ref)		0 (ref)		0 (ref)
SMOKER		0.009		0.2		0.2		0.06
yes	−0.719 (0.270)		−0.361 (0.250)		−0.273 (0.218)		0.338 (0.177)
no	0 (ref)		0 (ref)		0 (ref)		0 (ref)
BMI (kg/m2)	−0.024 (0.026)	0.3	−0.036 (0.024)	0.1	0.016 (0.021)	0.5	−0.047 (0.017)	0.007
AGE (years)	0.009 (0.010)	0.4	0.005 (0.009)	0.6	0.008 (0.008)	0.3	−2E−4 (0.006)	1.0
Random effects
${\sigma }_{w_{\mathit{full}}}^2$	0.156 (0.020)	<0.0001	0.112 (0.014)	<0.0001	0.264 (0.034)	<0.0001	0.200 (0.025)	<0.0001
${\sigma }_{b_{\mathit{full}}}^2$	0.236 (0.092)	0.005	0.205 (0.080)	0.005	0.130 (0.061)	0.02	0.083 (0.041)	0.02
wR0.95	4.70		3.71		7.49		5.77
bR0.95	6.71		5.90		4.11		3.09
ICCfull	0.602		0.647		0.330		0.293