Lead levels - blood

Alternative names
Blood lead levels

Definition
This is a test that measures the amount of lead in the blood.

How the test is performed

Blood is drawn from a vein, usually on the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and an elastic band is placed around the upper arm to apply pressure and restrict blood flow through the vein. This causes veins below the band to fill with blood.

A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the band is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

The blood is collected and transported in containers that do not contain lead. It is usually evaluated by atomic absorption spectroscopy.

How to prepare for the test
No dietary restriction of food or fluid is necessary.

If your child is to have this test performed it may be helpful to explain how the test will feel, and even practice or demonstrate on a doll. The more familiar your child is with what will happen to them, and the purpose for the procedure, the less anxiety they will feel.

How the test will feel
When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.

Why the test is performed
While lead serves no function in our bodies, it is usually present to some degree since it is so common in our environment. Low levels in adults are not thought to be harmful, but in infants and children, low levels of lead can lead to toxicity (see lead poisoning) such as deficits in intellectual/cognitive development.

This test is performed to screen people at risk for lead poisoning (such as industrial workers or children in urban areas), and to monitor the improvement of those who already have diagnosed increased serum lead levels, or lead toxicity.

Normal Values
Adults:

     
  • less than 20 micrograms/dL of lead in the blood

Children:

     
  • less than 10 micrograms/dL of lead in the blood

Note: dL = deciliter

What abnormal results mean
Adults:

     
  • greater than 30 micrograms/dL of lead in the blood

Children:

     
  • greater than 10 micrograms/dL of lead in the blood is abnormal and may be associated with intellectual deficits  
  • greater than 25 micrograms/dL of lead may indicate the need for treatment with a chelation agent such as calcium disodium edetate

If you have elevated lead levels, it is vital that you are separated immediately from the source of the lead. You should discuss possible sources of exposure and ways to eliminate the exposures with your health care provider.

Note: dL = deciliter

What the risks are
Risks associated with having blood drawn are slight:

     
  • excessive bleeding  
  • fainting or feeling light-headed  
  • hematoma (blood accumulating under the skin)  
  • infection (a slight risk any time the skin is broken)  
  • multiple punctures to locate veins

Special considerations
Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.

Johns Hopkins patient information

Last revised: December 4, 2012
by Janet G. Derge, M.D.

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All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.