Table 1.

Numbers of participants, observations, cystatin C (CysC) mean, intercept, and ß-slope of the LIFE Child cohort sorted in age intervals

		Infancy	Childhood	Adolescence		All
Age in years		0–2	2–11	11–15	15–18	0–18
Observations, n (%)	Males	213 (6)	1712 (52)	1002 (30)	363 (11)	3290 (100)
	Females	169 (6)	1433 (49)	895 (31)	430 (15)	2927 (100)
Participants	Males	180	903	540	245	1466
	Females	146	771	490	278	1337
CysC mean (±SD) in mg/l	Males	0.964 (0.149)	0.863 (0.106)	0.940 (0.128)	0.940 (0.117)	0.901 (0.124)
	Females	0.950 (0.134)	0.864 (0.105)	0.886 (0.123)	0.813 (0.108)	0.868 (0.117)
	t test	p > 0.05	p > 0.05	p < 0.001	p < 0.001	p < 0.001
CysC intercept in mg/l	Males	1.152	0.846	0.886	0.973	0.860
	Females	1.127	0.828	0.933	0.830	0.902
	p value	p > 0.05	p > 0.05	p < 0.001	p < 0.01	p < 0.001
CysC ß-slope in mg/l/a	Males	− 0.159	0.003	0.028	− 0.033	0.005
	Females	− 0.148	0.007	− 0.023	− 0.017	− 0.003
	p value	p > 0.05	p < 0.05	p < 0.001	p > 0.05	p < 0.001
Height mean (±SD) in cm	Males	78.2 (5.77)	124.9 (18.0)	161.4 (11.5)	176.6 (7.1)	138.7 (29.4)
	Females	76.3 (5.9)	123.5 (18.3)	159.7 (8.6)	166.5 (6.3)	138.2 (27.9)
Weight mean (±SD) in kg	Males	10.19 (1.67)	27.03 (10.91)	54.21 (16.10)	68.47 (16.78)	38.79 (21.59)
	Females	9.45 (1.68)	26.51 (11.21)	53.93 (15.27)	62.74 (15.41)	39.20 (21.11)
BMI mean (±SD) in kg/m2	Males	16.6 (1.2)	16.7 (3.0)	20.5 (4.6)	21.9 (4.8)	18.4 (4.3)
	Females	16.0 (1.1)	16.7 (3.1)	21.0 (5.0)	22.6 (5.3)	18.8 (4.8)

Age intervals were determined by visual inspection for better interpretation with linear regression models (see Fig. 2). Note that participants may have undergone various observations that belong to different age intervals. Intercepts and ß-slopes (in mg/l per year of life) were calculated with the lm-function in R. The intercept represents the mean CysC concentration of the first observations of each age interval

n number of observations, SD standard deviation, BMI body mass index