Lack of reversal effect of EDTA treatment on cadmium induced renal dysfunction: a fourteen-year follow-up

The aim of this study was to evaluate the effect of ethylenediaminetetraacetic acid (EDTA) on cadmium (Cd) induced renal dysfunction. Seventeen workers (14 males, 3 females) were diagnosed with occupational Cd poisoning in 1986. These individuals had between 7 to 39 years of Cd exposure. From 1986 to 1999, patients received periodic EDTA therapy as part of their follow-up, all at the same hospital. Levels of urinary cadmium (UCd) and urinary beta2-microglobulin (B2M) were measured before and after each annual EDTA treatment period. Renal dysfunction was defined as urinary B2M > 0.8 mg/g Cr (creatinine). In these workers, patients with UCd level higher than 10 microg/g Cr in 1986 had abnormal B2M excretions (> or = 0.8 mg/g Cr) or trended to have abnormal B2M levels during the treatment period. However, in subjects with UCd concentration lower than 10 microg/g Cr in 1986, their urinary B2M excretions either remained normal (< 0.8 mg/g Cr) or returned to normal during the treatment period. The prevalence of renal dysfunction increased during the follow up period regardless of whether UCd levels increased or not, indicating a progressive renal dysfunction despite removal from Cd exposure. Our results suggest that reversibility of renal dysfunction caused by Cd related to the level of Cd exposure at the time of removal from exposure: renal dysfunction could be reversed if initial UCd < 10 microg/g Cr, but was irreversible when UCd > 10 microg/g Cr. Repeated examinations on these 17 Cd exposed workers from 1986 to 1999 also revealed that periodic administration of EDTA had no beneficial effects on chronic Cd-induced renal dysfunction.