Slow, natural reduction in blood lead level after chelation therapy for lead poisoning in childhood.

Lead poisoning is treated with chelating agents. We report the natural decline of blood lead (Pb-B) concentration after treatment(s) (1967 to 1972) in 74 patients whose maximal Pb-B level ranged from 100 to 471 micrograms/dL (4.83 to 22.73 mumol/L). These longitudinal data (range, nine to 17 years) disclose a predictable decrease in Pb-B levels after treatment that is independent of the maximal Pb-B level before therapy. The correlation between age in months and the logarithm of the Pb-B level was significant, and the equation defined by the regression line allows one to predict Pb-B levels at specific ages after chelation therapy. It is important to recognize the slow, natural decline of Pb-B levels after chelation therapy once the level is stable and below 70 micrograms/dL (3.38 mumol/L). Multiple repeated courses of calcium disodium edetate are unlikely to influence the natural decline of the Pb-B level in asymptomatic children.

Renal function 9 to 17 years after childhood lead poisoning.

Renal function was studied in 74 subjects who, between 1966 and 1972 (ages 1 to 6 years) had had blood lead levels (PbB) greater than or equal to 100 micrograms/dl (range 100 to 471 micrograms/dl, median 142 micrograms/dl) and in 21 sibling controls. PbB measured in 1983 in study subjects remained significantly higher than in sibling controls (mean +/- 1 SD 14.5 +/- 4.5 vs 11.6 +/- 2.6 micrograms/dl, P less than 0.01). The two groups did not differ in development of hematuria or leukocyturia. The frequency of elevated serum creatinine concentration, depressed creatinine clearance, elevated protein excretion, low urinary osmolality, elevated serum beta 2-microglobulin (beta 2-M), and elevated fractional excretion beta 2-M % X 100 was similar in the two groups. Mean values for these tests were similar in study subjects compared with sibling controls. Mean systolic blood pressure was significantly higher in study subjects compared with that in sibling controls (117 +/- 12 vs 109 +/- 10 mm Hg), but the control group contained a preponderance of females and the study group had more overweight females; mean diastolic blood pressure was similar in the two groups. We conclude that in our adolescent subjects who had had lead poisoning 9 to 17 years earlier, there is little if any evidence of chronic nephropathy.