Chelation therapy for patients with elevated body lead burden and progressive renal insufficiency - A randomized, controlled trial

Background: Nephropathy is known to occur in persons exposed to high levels of lead, but the question of whether long-term exposure to low levels of e nvironmental lead is associated with impaired renal function remains contro versial. Objective: To examine whether chelation therapy stows the progression of re nal insufficiency in patients with mildly elevated body lead burden. Design: Randomized, controlled trial. Setting: Academic medical center in Taiwan. Patients: 32 patients with chronic renal insufficiency (serum creatinine le vel > 132.6 mu mol/L [1.5 mg/dL] and < 353.8 mu mol/L [4.0 mg/dL]), mildly elevated body lead burden (>0.72 mu mol [150 mu g] of lead per 72-hour urin e collection and < 2.90 mu mol [600 mu g] of lead per 72-hour urine collect ion [EDTA mobilization tests]), and no history of heavy lead exposure. Intervention: The treatment group received 2 months of chelation therapy; t he control group received no therapy. Measurements: The reciprocal of serum creatinine (1/Cr) was used as an inde x of progressive renal insufficiency. Results: Rates of progression of renal insufficiency were similar in the tr eatment group and the control group during a 12-month baseline observation period (1/Cr, 0.000054 L/mu mol per month compared with 0.000046 L/mu mol p er month; P > 0.2). After the 2-month treatment period, improvement in rena l function was greater in the treatment group than in the control group. In the 12 months after the treatment period, renal insufficiency progressed m ore slowly in the treatment group than in the control group (1/Cr, 0.000033 +/- 0.00038 L/mu mol per month compared with 0.000045 +/- 0.000038 L/mu mo l per month; P = 0.0030). Conclusion: Chelation therapy seems to slow the progression of renal insuff iciency in patients with mildly elevated body lead burden. This implies tha t long-term exposure to low levels of environmental lead may be associated with impaired renal function in patients with chronic renal disease.