How is Lead Poisoning Detected?
Lead poisoning usually is detected by measuring the level in blood. Many screening procedures use capillary blood as point-of-care testing. While finger-prick samples are appropriate for screening tests, all elevated capillary levels should have confirmation with a venous blood draw since capillary tests can yield frequent false positives. An elevated capillary lead level indicates that lead is in the child's environment even if the venous level is low, however, so primary prevention and education should be initiated.
The current Bright Futures/AAP Periodicity Schedule recommends a risk assessment at the following well-child visits: 6 months, 9 months, 12 months, 18 months, 24 months, and at 3, 4, 5 and 6 years of age. The recommendation is to do a risk assessment, and do a blood lead level test only if the risk assessment comes back positive. According to the AAP and CDC, universal screens or blood lead level tests are not recommended anymore except for high prevalence areas with increased risk factors as described in a 2012 CDC report, such as older housing.
Most initial blood lead level tests are now performed as a result of a positive risk assessment or parental concern rather than because children have symptoms that suggest lead poisoning. However, children of all ages who are recent immigrants, refugees, or adoptees are more likely to have elevated blood lead levels and should be screened at the earliest opportunity. Additionally, children who live in lower socioeconomic areas may be at higher risk.
Medicaid-eligible patients also tend to be at higher risk for lead exposure because many live in these lower socioeconomic areas. Many state Medicaid/Early and Periodic Screening, Diagnostic, and Treatment programs require a universal blood lead level test at the 12-month and 24-month visits, no matter the prevalence of elevated levels based on factors such as where the patient lives. While these programs have been directed to transition their requirements to be more in line with prevalence data (targeted screening), most states have not completed these efforts. For more information, see the CMCHS Information Bulletin, Target Lead Screening Plans or the CDC Guide For States Interested in Transitioning to Targeted Blood Lead Screening for Medicaid-Eligible Children. Pediatricians should ask their state Medicaid office to determine which requirements they should follow when it comes Medicaid-eligible patients. This information is available for most states on the CDC Web site. However, pediatricians may err on the side of caution and obtain a lead level in Medicaid patients and those who they feel are at high risk.
Because of lead's effects on the developing fetus, some states have developed lead screening guidelines for pregnant women. The CDC recently published guidelines on the screening of pregnant women for lead, medical and environmental management, and follow-up of mothers and infants when maternal lead levels are at least 5 micrograms per deciliter. Care of the infant includes measuring cord or neonatal blood lead to establish a baseline. Once the child is born, the guideline calls for an interruption of breastfeeding only if the maternal blood lead level is 40 micrograms per deciliter or more. Above this level, women should pump and discard their milk until after their blood lead level decreases below that benchmark.
For families using tap water to reconstitute infant formula or juice, or where there has been local concern, tap water testing may be recommended. To help determine whether a home's water might contain lead, parents can call the EPA Safe Drinking Water Hotline at (800) 426-4791 or their local health department to find out about water testing. Well water should be tested for lead when the well is new and tested again when a pregnant woman, infant or child less than 18 years of age moves into the home. For a discussion about using well water to feed infants, see the AAP policy statement on drinking water from private wells. Most water filters remove lead.
When is Diagnostic Testing Warranted?
Some experienced clinicians measure the blood lead level in children with growth retardation, speech or language dysfunction, anemia, and attentional or behavioral disorders, especially if the parents have a specific concern about lead or about health effects from environmental chemicals. However, elevated blood lead levels that continue into school age are unusual, even if peak blood lead level at 2 years of age was high and the child's home exposures have not been addressed. Therefore, a relatively low blood lead level in a school-aged child does not rule out earlier lead poisoning. If the question of current lead poisoning arises, however, the only reliable way to make a diagnosis is with blood lead measurement. Hair or urine lead levels give no useful information and should not be performed.
- CDC's Childhood Lead Poisoning Prevention Program
- CDC Low Level Exposure Harms Children: A Renewed Call for Primary Prevention
- Pediatric Environmental Health Specialty Unit
- CMCS Targeted Lead Screening Plans
- CMS Guide for States Interested in Transitioning to Targeted Blood Lead Screening for Medicaid-Eligible Children
- Blood Lead Levels in Children: What Parents Need to KnowWhere We Stand: Lead Screening
American Academy of Pediatrics