Table 1. Characteristics and elements distribution of the study population.

Characteristics	Overall (n=5,468)	Children without behavior problems (n=4,844)	Children with behavior problems (n=624)	P value
Age (year)	9.41 (7.57, 11.66)	9.49 (7.57, 11.74)	9.33 (7.66, 11.41)	0.50
Sex				0.40
Male	3,362 (61.49)	2,988 (61.68)	374 (59.94)
Female	2,106 (38.51)	1,856 (38.32)	250 (40.06)
Height (cm)	138.80 (127.50, 153.30)	139.00 (127.50, 154.00)	137.15 (127.20, 150.00)	0.08
Weight (kg)	31.20 (24.20, 44.00)	31.35 (24.20, 44.10)	30.55 (24.00, 43.12)	0.16
BMI (kg/m2)	16.04 (14.47, 18.92)	16.05 (14.48, 18.90)	15.93 (14.41, 18.98)	0.41
Weight status				0.62
Thin	486 (8.89)	422 (8.71)	64 (10.26)
Normal	3,741 (68.42)	3,319 (68.52)	422 (67.63)
Overweight	692 (12.66)	617 (12.74)	75 (12.02)
Obesity	549 (10.04)	486 (10.03)	63 (10.10)
Magnesium (mmol/L)	1.50 (1.39, 1.61)	1.50 (1.39, 1.61)	1.49 (1.39, 1.60)	0.048
Iron (mmol/L)	6.79 (6.28, 7.35)	6.81 (6.29, 7.36)	6.71 (6.19, 7.26)	0.001
Copper (μmol/L)	12.44 (11.02, 13.93)	12.45 (11.04, 13.93)	12.39 (10.90, 13.94)	0.74
Zinc (μmol/L)	67.25 (60.40, 74.81)	67.33 (60.51, 75.02)	66.70 (59.63, 73.37)	0.06
Lead (μg/L)	8.00 (6.00, 11.00)	8.00 (6.00, 11.00)	9.00 (7.00, 12.00)	<0.001
Calcium (mmol/L)	2.46 (2.41, 2.51)	2.46 (2.41, 2.51)	2.46 (2.41, 2.51)	0.29
Phosphorus (mmol/L)	1.66 (1.56, 1.77)	1.66 (1.56, 1.77)	1.67 (1.57, 1.77)	0.39
Triglycerides (mmol/L)	0.74 (0.56, 1.02)	0.73 (0.56, 1.01)	0.77 (0.57, 1.08)	0.09
High triglycerides				0.02
No	4,701 (85.97)	4,183 (86.35)	518 (83.01)
Yes	767 (14.03)	661 (13.65)	106 (16.99)
Vitamin D (nmol/L)	68.70 (53.50, 86.00)	68.90 (53.50, 86.40)	66.00 (53.80, 84.00)	0.07
Nutritional status of vitamin D				0.09
Sufficiency	4,434 (81.09)	3,933 (81.19)	501 (80.29)
Insufficiency	881 (16.11)	784 (16.18)	97 (15.54)
Deficiency	153 (2.80)	127 (2.62)	26 (4.17)

Values are median (interquartile range) or n (%) unless otherwise indicated. BMI, body mass index.