Background: Studies of the long term effects of childhood plumbism disagree on the significance of renal abnormalities. One early study found no evidence of renal dysfunction in patients who had experienced lead poisoning 9-17 years, but in a more recent report survivors of childhood lead poisoning had increased risk of hypertension developing in the setting of supranormal creatinine clearance. In adult males chronically exposed to lead N-acetyl-β-D-glucosaminidase (NAG) and α1-microglobulin(α1M) were the most sensitive indicators of lead-induced changes in the nephron. Aim: To determine whether NAG, α1M, andβ2-microblobulin (β2M) are useful markers of early renal dysfunction in children with elevated blood lead concentrations(CPB). Methods: Twenty patients (mean age 47.2 mos, range 13-94 mos) with elevated CPB (>8.0 μg/dL), no history of renal disease, and who were followed in the Lead Clinic of The Children's Hospital of The King's Daughters (CHKD) were studied. Twenty children with normal renal function (serum creatinine <0.8 mg/dL), no history of renal disease or existing urinary tract infection, and seen in the CHKD Well Child Clinic were enrolled as age- and weight-matched controls. Blood and urine specimens were collected for analysis of CPB, serum sodium (SNa), serum creatinine (SCr), serum β2M, urine creatinine, urine sodium, urine NAG, urine α1M, and urine β2M concentrations. Results: The study and control groups were similar for age, weight, race, and body mass index. SCr was slightly higher in the control group (0.48 vs. 0.51 mg/dL, p = 0.049), but FENa, FEβ2M, serum β2M, β2M Index, and NAG Index were not significantly different. Only 5 of 20 Lead Clinic patients had measurable amounts of urinary α1M (>0.40 mg/dL). The meanβ2M Index of those 5 patients was significantly higher than their matched controls (0.17 vs. 0.12, p = 0.043), and the other 15 clinic patients (0.17 vs. 0.11, p = 0.04). The maximum CPB of the 5 patients was also higher than the other clinic patients (33.7 μg/dL vs. 22.8 μg/dL, p = 0.091), although statistical significance was not achieved due to limited sample size. Conclusion: Urinaryα1M and β2M Index may be useful markers of early renal dysfunction in children exposed chronically to elevated CPB.
