Lead (Blood)

Serum lead level, BLL, blood lead test

This test measures the amount of lead in your child's blood. It can find out if your child has been exposed to lead.

Before 1978, lead was a major ingredient in household paint. It still can be found in older homes and in the soil around them. Children can inhale lead dust or chew on items with lead-based paint. There is no safe lead blood level for children. High levels of lead in the blood can be toxic.  

Your child may need this test if they are at high risk for lead exposure. Or if your insurance company needs lead testing in children. Children under the age of 6 are at particular risk for lead poisoning. Young children can touch objects that contain lead and then put their hands in their mouths. Children living in older housing or areas with lead pipes are also at a higher risk for lead poisoning. If you live in a home built before 1978, your doctor might order this test to see if your child has been exposed to lead. Children also are tested for lead if they have signs and symptoms of lead poisoning, including:

• Belly pain

• Anemia (low red blood cell counts)

• Nausea or vomiting

• Weight loss

• Extreme tiredness

• Muscle weakness

• Seizures

• Headache

• Hair loss

• Difficulty paying attention, behavior changes, or learning disabilities

This test is also used to see if treatment for lead poisoning is working.

If your child has higher than normal lead levels, their doctor might order a complete blood count. This checks for anemia, a condition in which the red blood count is low. If your child has anemia, their body may not get enough oxygen.

Your child may also have these blood tests:

• Reticulocyte count

• Serum iron

• Total iron-binding capacity

• Ferritin

For children who need treatment for lead poisoning, more tests may be needed to see if their kidneys and liver are working the way they should. These tests include:

• Serum electrolytes

• Blood urea nitrogen

• Creatinine

• Calcium

• Magnesium

• Liver function tests

• Urinalysis

Test results may vary depending on your child's age, gender, health history, and other things. Your child's test results may be different depending on the lab used. The results may not mean your child has a problem. Ask your doctor what your child's test results mean for them.

A test result greater than 3.5 micrograms per deciliter (mcg/dL) is considered high. It may mean your child has been exposed to lead. The higher the level of lead in your child's blood, the greater the risk of learning disabilities, impaired growth, and kidney and nerve damage.

The test is done with a blood sample. The sample is drawn through a needle from a vein in your child's arm. Blood samples from infants and children may also be collected by a finger stick. If test results from a finger stick are abnormal, a sample of blood drawn from a vein is usually done to confirm the results.

Having a blood test with a needle carries some risks. These include bleeding, infection, bruising, and feeling lightheaded. When the needle pricks your child's arm or finger, they may feel a slight sting or pain. Afterward, the site may be sore. 

The test results reflect only recent exposure to lead.

Your child may get a false test result if:

• Blood is taken from your child's finger and they have dust or dirt on their hands.

• Your child is not getting enough calcium, iron, and vitamin C and eating too much fat.

Your child doesn't need to prepare for this test. Be sure your doctor knows about all prescribed and over-the-counter medicines, herbs, vitamins, and supplements your child is taking. This includes drugs your child may use that have not been prescribed.