Failure of chelation therapy in lead nephropathy

A patient with lead nephropathy and gout was treated with three months of edetic acid chelation. The therapy resulted in normalization of a previously abnormal result of edetic acid lead mobilization test. Nevertheless, progressive renal insufficiency occurred. At autopsy, an increased bone lead content was documented, suggesting that the edetic acid lead mobilization test may underestimate total body lead stores and that chelation therapy may not be effective in reversing advanced lead nephropathy. Alternatively, a longer period of therapy may be necessary to remove lead stores. More studies are needed to determine the relationship between the results of the edetic acid test and bone lead stores. Methods other than the edetic acid lead mobilization test should be considered to monitor the adequacy of treatment in lead nephropathy.