RESUMEN
BACKGROUND: Although chelation therapy with calcium disodium ethylenediamine tetraacetic acid (CaNa2EDTA) reduces body burden of lead and improves clinical side effects from lead, it is unclear whether long-term repeated chelation is safe for chronic lead poisoning with nephropathy. We described the consequential changes of renal function and clinicopathological findings during one to two years of monthly administration of CaNa2EDTA in patients with chronic lead nephropathy and excessive body lead burden. METHODS: Three patients diagnosed as chronic lead nephropathy received 1 g/day of intravenous CaNa2EDTA for a 3-5 day/cycle. A total of 48-86 g CaNa2EDTA was administered. Midtibial bone lead, chelatable lead, and blood lead levels were assessed. Renal function was determined in each chelation, and renal biopsies before and after chelation were conducted and compared for microscopic and immunofluorescence changes. RESULTS: Cortical bone lead levels showed a high burden of lead (>200 microgram Pb/g bone mineral). During CaNa2EDTA treatment, blood lead level and renal function were in steady state. No evidence of progression of renal pathology was observed in both renal biopsies, showing similar interstitial fibrosis and glomerular sclerosis. CONCLUSION: Our results suggest that long-term repeated chelation therapy with CaNa2EDTA is safe and effective for patients who have suffered from severe chronic lead poisoning, even though renal pathologic change has started.