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Lead Toxicity

All children should be evaluated for lead toxicity because their developing nervous system makes them much more susceptible than adults. The most common sources of lead exposure are lead-based paint and lead-contaminated dust and lead poisoning. Seventy four percent of houses that were built before 1978 contain lead-based paint. Blood lead levels higher than 10 Fg/dL in children and pregnant women and above 40 Fg/dL in adults.

Sources of Lead Exposure

Environmental. Lead-based paint, leaded gasoline, lead solder in plumbing pipes, lead dust, lead chromate in plastics.

Food storage. Lead-glazed ceramic, lead crystal.

Occupational and recreational. Battery reclamation, precious metals refining, radiator repair, glazed pottery making, target shooting.

Other. Gunshot wounds.

Adverse Effects

Most patients with increased blood lead levels remain asymptomatic; however, blood levels as low as 10-30 Fg/dL can produce an IQ deficit of 4-5% in children.

Levels greater than 40 Fg/dL cause a decrease in hemoglobin synthesis that can lead to microcytic anemia. High concentrations of lead can cause nephropathy, neuropathy, increased intracranial pressure, seizures.

Treatment of Lead Toxicity

Environmental Changes. Avoidance of further lead exposure is the primary mode of treatment.

Dietary Modifications. Patients with iron deficiency have increased absorption of lead; therefore, iron deficiency should be treated. Adequate calcium, zinc, and protein may also reduce lead absorption.

Chelation Therapy

Treatment of acute poisoning consists of one or more chelating agents.

EDTA

This agent binds to lead and is excreted in urine. The usual daily dose is 1,000 mg/m² for 5 days, preferably administered intravenously. If the agent is given IM, procaine hydrochloride.

Succimer ( Chemet) is the only oral agent approved for chelation of lead. Efficacy is comparable to EDTA. is the only oral agent approved for chelation of lead. Efficacy is comparable to EDTA.

Succimer is given in doses of 10 mg/kg tid for 5 days and then bid for an additional 2 weeks. The adult dose is 500 mg tid for 5 doses, followed by 500 mg bid for 14 days.

Dimercaprol binds with lead and is excreted in urine and bile. Unlike EDTA, it chelates lead from the brain. Dimercaprol is commonly combined with EDTA to treat lead encephalopathy; urine is alkalinized during treatment.

Penicillamine ( Cuprimine, Depen) may be given for treatment of lead poisoning.