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

Delta aminolaevulinic acid dehydratase (ALA-D) was assayed in66 patients with end-stage renal failure who live in a regionwhere there is a high risk of lead poisoning from drinking water(Vosges mountains). Sixty patients received dialysis and sixunderwent renal transplantation. Results were compared to thoseobtained in 366 control subjects with normal renal functionhospitalized in a department of Internal Medicine and livingin the same geographical area. The ALA-D level was significantlylower in dialysed patients (0.40±20) than in controls(0.57±0.31) (P = 0.0014). Transplant recipients had ALA-Dlevels comparable to subjects with normal renal function (0.59± 0.37). In this high-risk population an EDTA test wasperformed in 74 subjects (with normal renal function and 17dialysis patients in combination with haemofiltration for thelatter patients. In the two study groups a negative correlationwas found between ALA-D and the amount of lead che-lated duringthe 24 h following administration of EDTA (r= –0.77 and–0.88 respectively). In subjects who live in an area ofendemic lead poisoning, the incidence of elevated body leadburden from drinking water was similar in the group with normalrenal function and in the group of dialysed patients (18.6 and8.3% respectively). This study shows (i) that in dialysis patients, measurementof ALA-D represents an accurate screening test for lead overload,provided that the lower threshold of normal is lowered from0.40 to 0.20, and (ii) that diagnosis and treatment are possibleby administering EDTA in conjunction with haemofiltration orCAPD.