Biochemical markers of renal function and blood lead levels. Results are shown as arithmetic mean, standard deviation, frequency and percentage [median].

Table 2: Biochemical markers of renal function and blood lead levels. Results are shown as arithmetic mean, standard deviation, frequency and percentage [median].

Category I

(< 25 µg/dL) (n = 367)

Category II

( > 25 - <45 µg/dL) (n = 87)

Category III

( > 45 µg/dL) (n = 26)

Urea nitrogen serum levels (mg/dL)

21.8 ± 6.8

[21.0]

21.3 ± 6.29

[22.0]

22.1 ± 7.2

[21.5]

Abnormal urea nitrogen level

(> 50.0 mg/dL)

Yes

367 100.0%

87 100.0%

26 100.0%

Creatinine serum level

(mg/dL)

0.74 ± 0.13

[0.73]

0.74 ± 0.18

[0.70]

0.74 ± 0.1

[0.79]

Abnormal creatinine levels (> 1.20 mg/dL)

Yes

17 4.6%

350 95.3%

8 9.2%

79 90.8%

1 3.8%

25 96.1%

Uric acid serum levels

(mg/dL)

4.6 ± 1.19

[4.5]

4.8 ± 1.48

[4.7]

4.9 ± 1.71

[4.35]

Abnormal uric acid levels (> 50.0 mg/dL)

Yes

13 3.5%

352 96.4%

9 10.3%*

78 89.6%

3 11.5%*

23 88.4%

Current proteinuria

Yes

16 4.3%

351 95.6%

2 2.3%

85 97.7%

26 100.0%

eGFR (mL/min/1.73m²)

108.6 ± 28.4

[103.7]

121.0 ± 26.9*

[115.8]

121.3 ± 25.2*

[115.8]

Zinc protoporphyrin (gr/mL)

3.2 ±2.5

[2.7]

2.5 ± 2.4*

[2.1]

2.3 ± 1.6

[1.8]

Baseline BLL (µg/dL)

9.0 ± 6.1

[7.4]

31.7 ± 8.4*

[31.6]

54.0 ±12.5*

[53.8]

Highest BLL (µg/dL)

10.2 ± 6.1

[8.6]

33.9 ± 7.3*

[32.8]

58.8 ± 7.4*

[59.6]

Last BLL (µg/dL)

3.0 ± 2.3

[2.5]

4.3 ± 4.2*

[3.1]

4.4 ± 2.66*

[4.0]

Years of follow-up

11.3 ± 4.3

[11.0]

14.4 ± 2.2*

[14.0]

14.3 ± 0.4*

[14.0]

Number of blood samples

6.0 ± 4.6

[4.0]

14.5 ± 9.1*

[13.0]

28 ±12.2*

[25.5]

*p < 0.05 Student’s t test, or Mann-Whitney test or Chi² test (category I vs category II or III)