How is chronic lead nephropathy treated?

Updated: Jan 16, 2020
  • Author: Pranay Kathuria, MD, FACP, FASN, FNKF; Chief Editor: Tarakad S Ramachandran, MBBS, MBA, MPH, FAAN, FACP, FAHA, FRCP, FRCPC, FRS, LRCP, MRCP, MRCS  more...
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Answer

Patients with chronic lead nephropathy, in the absence of marked interstitial fibrosis and with only minimal impairment in kidney function, may respond to chelation therapy.

Extremely limited data are available regarding the benefits of chelation therapy with documented lead nephropathy. In 1979, Wedeen et al treated patients with occupational lead nephropathy and found a 20% improvement in the GFR in 4 of 8 patients given EDTA 3 times a week for 6-50 months. [35] The reported improvements in kidney function could be from reversal of acute-on-chronic lead nephropathy.

Lin and coworkers from Taiwan performed 3 well-designed studies addressing populations of patients with high-normal BLLs and chronic kidney disease. [36, 37, 38]

The first of these studies included 32 subjects with chronic kidney disease (serum creatinine level [SCr] of 1.5-4 mg/dL) and mildly elevated body lead burden (lead excretion value of 150-600 µg with the 3-D CaNa2 EDTA lead mobilization test). Subjects were randomly assigned to receive EDTA chelation therapy or placebo weekly for 2 months and were followed for an additional 12 months. The reciprocal of serum creatinine (1/SCr) versus time data suggested that using chelation may slow the progression of renal disease.

The second study described the results of chelation therapy in 36 subjects (24 study group subjects and 12 controls) with serum creatinine values of 1.5-4 mg/dL and high-normal bone lead burden. This time, chelation therapy with CaNa2 EDTA was administered weekly for 3 months. In the treated group, creatinine clearance improved by as much as 10.2% at 1 year, whereas in the control group, kidney function declined by as much as 11%.

The third study included 202 subjects who were followed for 2 years. In this study, 64 patients with a high-normal body lead burden (urinary lead excretion > 80 µg and < 600 µg after 1 g of CaNa2 EDTA infusion) and SCr lower than 4.2 mg/dL were randomized to chelation or placebo.

In the initial 3 months, the chelation group received 1 g of CaNa2 EDTA every week, and the controls received placebo. In the ensuing 24 months, repeated chelation therapy was administered weekly to patients with a high-normal lead burden unless, on repeated testing, the body lead burden fell below 60 µg.

The glomerular filtration ate (GFR) increased by 11.9% (+3.4 mL/min) in the chelation group at the end of the initial 3 months, whereas it fell by 3.6% (-1 mL/min) in the control group. Thereafter, no further improvement in the GFR was observed in these patients. At the end of 27 months, the mean change in GFR was +2.1 mL/min in the chelation group and -6 mL/min in the control group over the 27-month study.

These studies suggest that in patients with an increased lead burden, chelation with small doses of CaNa2 EDTA at longer intervals might be safe for treating chronic kidney disease. However, repeated and chronic exposure to CaNa2 EDTA may create its own nephrotoxicity; therefore, use caution when deciding to institute chelation therapy. Exclude other causes of kidney disease, and define an endpoint of therapy, such as normalization of the CaNa2 EDTA test results or improvement in kidney function.


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