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Table 1 Weighted characteristics of study population based on LnBLL quartiles

From: Association of low-level blood lead with serum uric acid in U.S. adolescents: a cross-sectional study

Variables* LnBLL quartiles, μg/dL  
Q1 (< −0.22) Q2 (−0.22–0.18) Q3 (0.18–0.64) Q4 (≥ 0.64) P value
N 2584 2447 1918 1354  
Male, % 34.08 (1.29) 51.28 (1.57) 66.88 (1.65) 77.39 (1.83) <  0.001
Age, years 15.63 (0.08) 15.52 (0.08) 15.30 (0.08) 15.18 (0.12) <  0.001
BMI, kg/m 23.86 (0.18) 23.50 (0.18) 22.99 (0.19) 22.71 (0.22) <  0.001
SBP, mm Hg 108.98 (0.44) 109.62 (0.29) 110.06 (0.34) 109.92 (0.58) 0.062
DBP, mm Hg 61.57 (0.47) 61.69 (0.40) 60.72 (0.63) 59.74 (0.55) 0.029
Race, %      <  0.001
 Non-Hispanic White 69.94 (1.79) 63.49 (2.13) 53.16 (2.3) 42.45 (3.48)  
 Non-Hispanic Black 10.07 (1.34) 13.92 (1.22) 19.41 (1.71) 23.11 (2.63)  
 Mexican American 9.78 (0.99) 9.87 (1.04) 12.60 (1.54) 18.35 (2.31)  
 Other Hispanic 5.26 (0.79) 6.25 (1.04) 6.79 (1.24) 8.68 (1.69)  
 Other race 4.95 (0.75) 6.47 (0.91) 8.04 (1.51) 7.41 (2.29)  
Education, %      <  0.001
  < high school 82.09 (1.40) 81.35 (1.54) 85.28 (1.5) 87.23 (1.54)  
 High school 8.8 (0.88) 9.53 (1.15) 9.00 (1.33) 5.84 (0.90)  
  > high school 9.11 (0.99) 9.12 (0.92) 5.72 (0.85) 6.93 (1.13)  
Physical Activity, %      <  0.001
 Sedentary 10.6 (1.03) 10.87 (1.26) 12.31 (2.04) 21.03 (3.02)  
 Low 25.47 (1.84) 23.96 (1.79) 21.5 (2.44) 19.15 (2.45)  
 Moderate 20.73 (1.27) 14.67 (1.35) 18.85 (2.36) 14.38 (2.26)  
 High 43.2 (1.87) 50.49 (1.67) 47.33 (2.64) 45.45 (3.42)  
Dietary
 Calcium, mg 1034.90 (20.30) 983.62 (18.67) 1014.37 (27.42) 927.54 (29.86) 0.032
 TMFA, gm 30.44 (0.46) 32.1 (0.49) 32.67 (0.57) 31.99 (0.83) 0.024
 TPFA, gm 16.08 (0.29) 16.29 (0.33) 16.94 (0.34) 16.49 (0.46) 0.175
 TSFA, gm 28.41 (0.45) 29.72 (0.46) 30.43 (0.6) 29.48 (0.86) 0.058
 Total fat, gm 81.35 (1.22) 84.92 (1.23) 87.02 (1.52) 84.88 (2.19) 0.035
 Protein, gm 77.83 (1.20) 79.85 (1.15) 83.67 (1.68) 82.47 (2.10) 0.009
Laboratory data
 Blood cadmium, ug/L 0.27 (0.01) 0.32 (0.01) 0.40 (0.02) 0.40 (0.02) <  0.001
 Serum cotinine, ng/mL 11.42 (1.23) 22.91 (2.00) 36.13 (3.69) 39.03 (5.15) <  0.001
 Hemoglobin, g/dL 14.07 (0.05) 14.36 (0.06) 14.54 (0.05) 14.58 (0.07) <  0.001
 FBG, mg/dL 86.23 (0.49) 86.1 (0.29) 87.06 (0.43) 87.90 (0.41) 0.018
 TC, mg/dL 163.98 (0.87) 161.76 (1.02) 160.58 (1.39) 159.64 (1.04) 0.001
 Triglycerides, mg/dL 96.07 (2.41) 92.13 (1.55) 89.82 (1.88) 90.03 (1.68) 0.015
 HDL-C, mg/dL 51.09 (0.32) 50.13 (0.36) 49.24 (0.46) 48.66 (0.48) <  0.001
 eGFR, mL/min per 1.73 m2 139.97 (0.73) 145.55 (0.8) 148.76 (0.92) 147.83 (0.76) <  0.001
 SUA, mg/dL 4.85 (0.04) 5.16 (0.04) 5.26 (0.04) 5.41 (0.06) <  0.001
 BUN, mg/dL 10.41 (0.13) 10.57 (0.13) 10.96 (0.13) 10.86 (0.18) 0.006
 CRP, mg/dL 0.20 (0.01) 0.18 (0.01) 0.15 (0.01) 0.15 (0.02) 0.001
  1. Abbreviations: BLL blood lead levels; BMI body mass index, SBP systolic blood pressure, DBP diastolic blood pressure, TMFA total monounsaturated fatty acids, TPFA total polyunsaturated fatty acids, TSFA total saturated fatty acids, FBG fasting blood glucose, TC total cholesterol, HDL-C high density lipoprotein cholesterol, eGFR estimated glomerular filtration rate, SUA serum uric acid, BUN blood urea nitrogen, CRP C-reactive protein
  2. *Data are presented as weighted means, proportions and Se
  3. The Physical Activity categories were based on the distribution of MET-minute levels for the present NHANES sample
  4. §BMI was calculated as the body weight in kilograms divided by the square of the height in meters
  5. Convert to BLL quartiles range: < 0.8 μg/dL, 0.8–1.2 μg/dL, 1.2–1.9 μg/dL, ≥ 1.9 μg/dL