#90: Lead Screening

August 1, 2023 | By Sam Masur

Audio

Summary:

In this episode, our guest Dr. Marissa Hauptman teaches us why we screen for lead exposure, what to do with an elevated lead level, and how to take an environmental exposure history.  Dr. Hauptman is the co-director for the Boston Children’s Hospital Pediatric Environmental Health Center, where she provides care for children with lead, asthma, and other environmental exposures.

Lead Screening Pearls

1. Children should be screened for lead exposure at age 12 and 24 months, or once between ages 24-72 months if they have never been tested.
2. There is no safe level of lead exposure – the CDC requires that action be taken at any level >3.5 µg/dL.
3. Consequences of lead exposure include neurodevelopmental delay, anemia, abdominal colic, lead encephalopathy, seizures, and death.
4. When taking an environmental history, use the H-HOMES mnemonic: Housing, H2O, Oxygen, Mites/Pests, Exposures, and Stressors.
5. Chelation therapy should be initiated when the blood lead level is >45 µg/dL. Prior to initiation of therapy, obtain baseline labs including repeat lead level, CBC with differential, iron studies, basic metabolic panel, hepatic panel, urinalysis, and zinc erythrocyte protoporphyrin.

Reach out to PEHSU or Poison Control (1800-222-1222) for assistance with managing lead exposure.

Lead Screening Notes

Lead Screening

The CDC  projects that 500,000 children in the US have a lead level >3.5 µg/dL. All children who receive Medicaid are required to be tested for lead and 12 and 24 months of age, or once between ages 24-72 months if they have never been screened. The CDC requires that further action be taken with any lead level >3.5 µg/dL. 

Capillary Stick – Can be beneficial as it is less traumatic for the child and their family and provides faster results. If the level is >3.5 µg/dL, then the patient needs a confirmatory venous blood draw. Expert opinion: even a “false positive” can be a warning sign that there is lead in the environment that has not yet made it to the child’s bloodstream.

Venous Sample – Gold standard for assessing lead level but can be more difficult for some patients.

Impact of Lead Exposure

Young children are at higher risk for consequences of lead exposure due to their still developing blood brain barrier and organs. Dr. Hauptman reminds us that there is no safe level of lead in a child’s blood. Lanphear et al. found that even “low” lead levels <10 µg/dL have measurable impacts on a child’s IQ. Consequences of lead exposure include:

• Neurodevelopmental delay
• Anemia
• Abdominal colic
• Lead encephalopathy
• Seizures

Taking an Environmental History

Think about where kids live, learn, work, and play. Dr. Hauptman uses the mnemonic H-HOMES. When thinking specifically about lead exposure, possible sources include: lead paint, contaminated soil, water supply, imported cookware, jewelry, and occupational exposures (ex. lead bullets at shooting range, stained glass, soldering). As they become more mobile, young children can be exposed through normal hand-mouth behavior while exploring their environment and through pica behaviors.

• Housing (type, date built especially if pre-1978, paint)

• H2O (source of water, lead pipes)

• Oxygen (air quality)

• Mites/Pests

• Exposures 

• Stressors/Social Determinants of Health – Environmental racism plays a role in the burden of lead exposure, and studies have shown that children living in the highest quintiles of old housing and poverty have the highest risk of elevated lead levels.

Counseling Families

Practical steps that families can take at home to reduce lead exposure include using duct tape or contact paper to cover up peeling lead paint, frequent wet mopping, hand washing, taking shoes off at the door, and getting their home formally inspected for lead. From a developmental standpoint, a study by Stingone et al. demonstrated that early intervention for children exposed to lead can improve academic performance later in life.

Managing Elevated Lead Levels

Dr. Hauptman encourages providers to reach out to resources including the Pediatric Environmental Health Specialty Units, which is a regional network of experts that can guide primary care providers and manage treatment and Poison Control (1-800-222-1222). The CDC also provides recommended actions based on blood lead levels. 

BLL 3.5-19 µg/dL

• Take thorough environmental exposure history. 
• Report to local health department.
• Ensure adequate iron and calcium intake (compete with lead for absorption) – if anemic can consider empiric iron supplementation.
• Repeat venous blood level in 1-3 months – additional labs to check include CBC, iron studies, and CRP.

BLL 20-44 µg/dL

• Assess for signs and symptoms of lead exposure with complete history and physical.
• Consider abdominal x-ray to check for lead chips (especially if pica behaviors) – if identified in stomach or small intestine, can do GI decontamination with polyethylene glycol.
• Repeat venous blood level within 1 month.

BLL >45 µg/dL

• May require admission to the hospital, especially to allow for assessment of the home environment for exposures to ensure that it is lead-safe upon return.
• Initiate chelation therapy.

Chelation Therapy

The overall goal of chelation therapy is to make lead water-soluble so that it can be eliminated via urine. Check baseline labs: repeat lead level, CBC with differential, iron studies, basic metabolic panel, hepatic panel, urinalysis, and zinc erythrocyte protoporphyrin.

Dimercaprol (British Anti-Lewisite)

Consider when lead level >70 µg/dL or concern for lead encephalopathy because it crosses the blood-brain barrier. Delivered IM and manufactured in peanut oil so cannot be used if peanut allergies. 

Calcium Disodium Edetate (EDTA)

Consider when lead level 45-69 µg/dL. Can cause increased lead concentration in the central nervous system so generally administered after dimercaprol. Delivered IV for ~5 day course and should be run with maintenance fluids due to risk of nephrotoxicity (check frequent UAs).

Succimer 

PO version of dimercaprol and equally effective as EDTA in asymptomatic children with lead level 45-69 µg/dL. Sulfur component can make the medication difficult to administer. Often given as a 21 day course by itself or following parenteral treatment with EDTA. Monitor for hepatotoxicity, GI upset, and neutropenia. Once outpatient, should repeat venous blood lead level in 1-2 weeks due to rebound from re-equilibration of lead from other body compartments.

Goal

Listeners will explain the importance of lead screening in the United States and management of elevated blood lead levels including public health interventions, laboratory monitoring, and chelation therapy.

Learning objectives

After listening to this episode listeners will be able to…  

1. Identify risk factors for lead exposure during early childhood. 
2. Discuss the ages that children should undergo lead screening
3. Recognize the signs and symptoms of lead poisoning.
4. Describe the indications and options for lead chelation therapy.
5. Counsel families on strategies to support lead-safe homes.

Disclosures

Dr. Hautpman reports no relevant financial disclosures. The Cribsiders report no relevant financial disclosures. 

Citation

Mao C, Hauptman M, Cruz M, Masur S, Chiu C, Berk J. “#90: Lead Screening”. The Cribsiders Pediatric Podcast. https://www.thecribsiders.com/ August 2, 2023.