Elevated body lead burden from drinking water in end-stage chronic renal failure

Delta aminolaevulinic acid dehydratase (ALA-D) who assayed in 66 patients with end-stage renal failure who live in a region where there is a high risk of lead poisoning from drinking water (Vosges mountains). Sixty patients received dialysis and six underwent renal transplantation. Results were compared to those obtained in 366 control subjects with normal renal function hospitalized in a department of Internal Medicine and living in the same geographical area. The ALA-D level was significantly lower in dialysed patients (0.40 +/- 20) than in controls (0.57 +/- 0.31) (P = 0.0014). Transplant recipients had ALA-D levels comparable to subjects with normal renal function (0.59 +/- 0.37). In this high-risk population an EDTA test was performed in 74 subjects (with normal renal function and 17 dialysis patients in combination with haemofiltration for the latter patients. In the two study groups a negative correlation was found between ALA-D and the amount of lead chelated during the 24 h following administration of EDTA (r = -0.77 and -0.88 respectively). In subjects who live in an area of endemic lead poisoning, the incidence of elevated body lead burden from drinking water was similar in the group with normal renal function and in the group of dialysed patients (18.6 and 8.3% respectively). This study shows (i) that in dialysis patients, measurement of ALA-D represents an accurate screening test for lead overload, provided that the lower threshold of normal is lowered from 0.40 to 0.20, and (ii) that diagnosis and treatment are possible by administering EDTA in conjunction with haemofiltration or CAPD.