Blood lead test results: who is tested, when, and what 3.5 µg/dL means
A blood lead test measures the amount of lead in the blood. (MedlinePlus, blood lead level) Lead is especially dangerous for children: even at low levels it can affect a child's mental and physical growth. (MedlinePlus, lead poisoning) CDC says no safe blood lead level in children has been identified. (CDC MMWR, 2021)
Which children are tested
Children with Medicaid must be tested at ages 12 and 24 months, or between 24 and 72 months if they were not tested before. This is a Centers for Medicare & Medicaid Services requirement. (CDC MMWR, 2021)
For other children, CDC says public health and clinical professionals should build screening plans that fit local conditions, and where there is no such plan, it recommends testing all children. (CDC MMWR, 2021) The AAP Bright Futures schedule lists these lead checks: (AAP Bright Futures, 2025)
| Age | What is done |
|---|---|
| 6 and 9 months | Risk assessment. (AAP Bright Futures, 2025) |
| 12 months | Risk assessment or blood test; a blood test for children with Medicaid or in high-prevalence areas. (AAP Bright Futures, 2025) (CDC MMWR, 2021) |
| 18 months | Risk assessment. (AAP Bright Futures, 2025) |
| 24 months | Risk assessment or blood test; a blood test for children with Medicaid or in high-prevalence areas. (AAP Bright Futures, 2025) (CDC MMWR, 2021) |
| 24 to 72 months, never tested | Medicaid requires a blood test if the child was not tested before. (CDC MMWR, 2021) |
| 3, 4, 5 and 6 years | Risk assessment. (AAP Bright Futures, 2025) |
In the schedule, a risk assessment is done with appropriate action to follow if it is positive. (AAP Bright Futures, 2025) The USPSTF found that questionnaires and other prediction tools are inaccurate at finding children without symptoms who have raised blood lead. (USPSTF, 2019)
Ways people can be exposed to lead include older homes with lead paint, water pipes in older homes, jobs or hobbies that use lead (such as stained glass or lead-glazed pottery), and some folk remedies. (MedlinePlus, lead poisoning) Many homes built before 1978 contain lead-based paint. (CDC MMWR, 2021)
Finger prick or vein
- How blood is taken: most often from a vein inside the elbow or on the back of the hand. In babies and young children, a small sharp tool (lancet) may be used to prick the skin instead. No special preparation is needed. (MedlinePlus, blood lead level)
- Finger-prick (capillary) samples: the USPSTF found that capillary blood testing accurately identifies children with raised blood lead. (USPSTF, 2019) CDC notes that skin prick samples can be contaminated with lead from the environment, so blood from a vein is less likely to have this contamination. (CDC MMWR, 2021)
- Confirming a result: CDC recommends follow-up testing to confirm a blood lead level. (CDC MMWR, 2021)
Helping a child know how the test will feel and why it is done may make them feel less nervous. (MedlinePlus, blood lead level)
What the results mean
MedlinePlus gives values in micrograms per deciliter (µg/dL) and micromoles per liter (µmol/L). Normal ranges may vary slightly between labs. (MedlinePlus, blood lead level)
| Child's blood lead level | What it means |
|---|---|
| Below 3.5 µg/dL (below 0.17 µmol/L) | The MedlinePlus normal value for children. CDC notes there is no known safe blood lead level. (MedlinePlus, blood lead level) (CDC MMWR, 2021) |
| 3.5 µg/dL or higher (0.17 µmol/L or higher) | At or above the CDC reference value. MedlinePlus says this needs further testing and monitoring, and the source of lead must be found and removed. (CDC MMWR, 2021) (MedlinePlus, blood lead level) |
The CDC blood lead reference value
- 3.5 µg/dL since 2021: CDC lowered it from 5 µg/dL, the value set in 2012. (CDC MMWR, 2021)
- How it is set: it is the 97.5th percentile of blood lead in US children aged 1 to 5, so about 2.5% of these children are at or above it. It is not a health-based standard or a toxicity threshold. (CDC MMWR, 2021)
- What it is used for: to help decide whether medical or environmental follow-up should start for a child, and to find the communities with the most need for prevention. (CDC MMWR, 2021)
What a result at or above 3.5 leads to
- Further testing to confirm the level, and monitoring. (CDC MMWR, 2021) (MedlinePlus, blood lead level)
- Finding and removing the source of lead. (MedlinePlus, blood lead level) Providers can give guidance on reducing exposure and link children to health departments for services. (CDC MMWR, 2021)
- Whether a level at or above the reference value triggers medical or environmental follow-up depends on the laws, rules and resources where you live. (CDC MMWR, 2021)
- After the lead source is dealt with, CDC says follow-up testing with blood from a vein should check that exposure went down, along with checks on development at regular intervals. (CDC MMWR, 2021)
CDC strongly advises providers to follow its Recommended Actions Based on Blood Lead Level. (CDC MMWR, 2021)
Adults
MedlinePlus gives less than 10 µg/dL (0.48 µmol/L) as normal for adults, and also says a level of 5 µg/dL (0.24 µmol/L) or above is considered elevated in adults. (MedlinePlus, blood lead level) The test is used to screen people at risk, such as industrial workers. (MedlinePlus, blood lead level)
Where they differ:
- Children without symptoms: the USPSTF found too little evidence to weigh benefits and harms of screening children 5 and younger (I statement, 2019). (USPSTF, 2019) It has since listed the topic as inactive, will not update it, and points to CDC guidance. (USPSTF, inactive topic) CDC recommends testing all children where there is no local screening plan, (CDC MMWR, 2021) and the AAP lists risk assessments at well-child visits, with blood tests at 12 and 24 months for children with Medicaid or in high-prevalence areas. (AAP Bright Futures, 2025)
- Questionnaires: the AAP schedule uses risk assessments at most visits, (AAP Bright Futures, 2025) while the USPSTF found that questionnaires are inaccurate at finding children with raised blood lead. (USPSTF, 2019)
- The cut-off used: the USPSTF 2019 review defined a raised level as 5 µg/dL, the CDC value at the time, (USPSTF, 2019) while the CDC value has been 3.5 µg/dL since 2021. (CDC MMWR, 2021)
- Pregnancy: the USPSTF found too little evidence to recommend for or against screening pregnant people without symptoms (I statement, 2019), (USPSTF, 2019) and refers to CDC guidance on lead and pregnancy. (USPSTF, inactive topic)
Your doctor decides what your result means for you.
This page does not give treatment or chelation advice. If you have a flagged result, see after an abnormal screening result for questions to ask.
Questions people ask
What is a normal blood lead level for a child?
MedlinePlus gives less than 3.5 µg/dL as the normal value for children. This matches the CDC blood lead reference value, set at 3.5 µg/dL in 2021. CDC says no safe blood lead level in children has been identified. (MedlinePlus, blood lead level) (CDC MMWR, 2021)
Is 3.5 µg/dL a toxic level?
No. CDC says the reference value is not a health-based standard or a toxicity threshold. It marks the level above which a child has more lead than 97.5% of US children aged 1 to 5, and it is used to decide whether medical or environmental follow-up should start. (CDC MMWR, 2021)
Why was my child retested with blood from a vein?
CDC recommends follow-up testing to confirm a blood lead level. It notes that skin prick samples can be contaminated with lead from the environment, and blood from a vein is less likely to have this contamination. (CDC MMWR, 2021)
At what ages are children tested for lead?
The AAP schedule lists a lead risk assessment at 6, 9 and 18 months and at 3 to 6 years, and a risk assessment or blood test at 12 and 24 months. Children with Medicaid must have a blood test at 12 and 24 months, or between 24 and 72 months if they were not tested before. (AAP Bright Futures, 2025) (CDC MMWR, 2021)
Should I be tested for lead during pregnancy?
The USPSTF found too little evidence to weigh the benefits and harms of screening pregnant people without symptoms (I statement, 2019), and it will not update that recommendation. It points to CDC guidance on lead and pregnancy instead. (USPSTF, 2019) (USPSTF, inactive topic)