In order to screen for abstruse
lead poisoning in
continuous ambulatory peritoneal dialysis (
CAPD) patients,
delta-aminolevulinic acid dehydratase (ALAD) levels were measured in 18
CAPD patients, 156 patients treated with
hemodialysis (HD), and 420 control patients with normal renal function (NRF). An
EDTA (
ethylenediamine tetraacetic
acid) mobilization test was performed in patients with low levels of ALAD (< 0.40 mumol of
porphobilinogen formed per milliliter of red blood cells): 1 g of
EDTA was infused IV followed by 20 L of hemofiltrate in HD patients and four bags of
dialysate in
CAPD patients. Lead was assayed in the ultrafiltrate liquid, the bags of
dialysate, and in the 24-hour urine. ALAD levels were significantly lower in
CAPD and HD patients than in the NRF subjects. ALAD was significantly correlated with
EDTA mobilized lead in both dialysis and NRF patients. Using the usual criteria (
EDTA mobilized lead > 800 micrograms/24 hours), the rate of
lead poisoning observed was similar in the two groups. These results suggest that ALAD assay followed by the
EDTA mobilization test is as effective in
CAPD patients as in NRF subjects to diagnose and to treat chronic abstruse
lead poisoning.