Long-Term Lead Chelation Therapy and Progressive Renal Insufficiency

Inclusion Criteria: * Patients from 18 through 80 years of age who had chronic renal insufficiency were eligible if they had a serum creatinine concentration between 1.5 mg per deciliter (132.6 μmol per liter) and 3.9 mg per deciliter (344.8 μmol per liter), with a decrease in the glomerular filtration rate of less than 5 ml per minute over a period of at least six months * Blood pressure less than 140/90 mm Hg * A cholesterol level below 240 mg per deciliter * Daily protein intake under 1 g per kilogram of body weight * No known history of exposure to lead or other heavy metals, and a high-normal body lead burden (between 60 and 600 μg, as measured by EDTA mobilization testing and 72-hour urine collection). Exclusion Criteria: * Patients who have renal insufficiency with a potentially reversible cause, such as malignant hypertension, urinary tract infection, hypercalcemia, or drug-induced nephrotoxic effects * Systemic diseases, such as connective-tissue diseases or diabetes mellitus * Use of drugs that might alter the course of renal disease, such as nonsteroidal anti-inflammatory agents, steroids, or immunosuppressive drugs * Rapidly progressive glomerulonephritis or a high level of 24-hour urinary protein excretion (more than 8 g per day) * Previous marked exposure to lead and other metals(lead poisoning or occupational exposure) * Drug allergies * Absence of informed consent.