If a child’s BLL value has not decreased or increased slightly (<4 μg/dL) within the recommended follow-up testing period, it could mean the child is still being exposed to lead. It could also reflect variability in laboratory testing or seasonal trends. Clinical Laboratory Improvements Amendments (CLIA) Proficiency testing criteria allow for a margin of error of ±4 µg/dL or ±10%, whichever is greater. BLLs also show seasonal variations, peaking in the summer months. If the BLL has gone up by greater than 4 μg/dL, it is likely the child is still being exposed to lead in their diet or environment. Reassess for potential lead exposure sources. If a likely source is identified, provide guidance on eliminating or reducing the child’s exposure and retest the child within the recommended time frame for their BLL. We recommend collaborating with the Childhood Lead Poisoning Prevention Program (CLPPP) in your area to help identify and mitigate the source of the exposure. Depending on the program’s case management protocol, they may be able to visit the home, do lead environmental lead testing, or offer other services. Contact your regional PEHSU to talk to a specialist if you have concerns about follow-up test results or need assistance identifying potential lead sources.