[Case of lead nephropathy due to chronic occupational lead exposure].

We report a case of a patient with chronic kidney disease likely due to lead nephropathy. He was a manufacturer of Buddhist altar fittings and had chronic lead exposure. The blood lead level was 41 microg/dL and urinary lead excretion at 24 hours after the administration of ethylenediaminetetraacetic acid (EDTA)was 600 microg (first time)and 687 microg (second time), respectively. Urinary lead excretion at 72 hours was 834 microg (first time) and 1,071 microg (second time), respectively. Renal biopsy showed interstitial fibrosis and focal monocyte infiltration. Lead content in the renal biopsy specimen was 130 ng/g of wet weight. We preformed weekly EDTA chelation therapy twelve times. During the therapy, serum creatinine was 1.1 mg/dL. The chelation therapy was interrupted by an episode of acute renal failure due to hypotension and heart failure. Urinary lead excretion exceeding 600 microg at 72 hours after chelation therapy indicated a lead body burden capable of causing lead nephropathy. In this case, urinary lead excretion exceeded 600 microg at 72 hours. Based on the report that repeated lead chelation therapy can slow the progression of non-diabetic chronic kidney disease with 72-hour-urinary lead excretion of 60-600 microg, we performed chelation therapy. This case suggests that lead nephropathy currently can occur in Japan. It is possible that renal dysfunction from lead nephropathy is reversed by minimizing lead exposure and chelation therapy. Lead nephropathy should be included in the differenitial diagnosis of causes of chronic kidney disease and occupational and environmental lead exposure should be investigated carefully during the medical history.