Test Overview
This test measures the amount of lead in the blood. Lead is a
poisonous (toxic) metal that can damage the brain and other parts of the body.
A lead blood test may be done on blood drawn from the vein, a finger (finger
stick), or the heel (heel stick).
A person can be exposed to
lead:
- By eating or drinking lead-contaminated foods,
water, or other material (such as paint chips).
- By breathing dust
or smoke containing lead.
- Through skin contact with lead.
There is no safe age to be exposed to lead. Adults can have
problems from
lead poisoning, but it is most harmful to children
younger than age 6 (especially those younger than age 3) because it can
permanently affect their growth and development. A pregnant woman who is
exposed to lead can pass it to her baby
(fetus). Lead can also be passed to a baby through the
mother's breast milk.
Why It Is Done
A lead blood test is done to:
- Diagnose lead poisoning.
- See how
well treatment for lead poisoning is working.
- Look for lead
poisoning in people who work with lead or lead products or live in places where
the chance of poisoning is high, such as in a large city.
- Check the amount of lead in people who live with or play with children who have lead poisoning.
How To Prepare
No special preparation is required
before having this test.
Be sure to tell your doctor if you are
using any herbal medicines.
How It Is Done
Blood tests for lead should be done by a
lab experienced in
proper technique.
Blood sample from a heel stick
For a heel stick
blood sample, several drops of blood are collected from the heel of your baby.
The skin of the heel is first cleaned with alcohol and then punctured with a
small sterile lancet. Several drops of blood are collected in a small tube.
When enough blood has been collected, a gauze pad or cotton ball is placed over
the puncture site. Pressure is maintained on the puncture site briefly, and
then a small bandage is usually applied.
A heel stick must be done
carefully to prevent contamination of the sample from lead on the skin. If a
heel stick blood sample comes back positive for lead, a sample of blood from
your baby's vein will be tested to confirm the results.
Blood sample from a vein
The health professional
taking a sample of your blood will:
- Wrap an elastic band around your upper arm to
stop the flow of blood. This makes the veins below the band larger so it is
easier to put a needle into the vein.
- Clean the needle site with
alcohol.
- Put the needle into the vein. More than one needle stick
may be needed.
- Attach a tube to the needle to fill it with
blood.
- Remove the band from your arm when enough blood is
collected.
- Put a gauze pad or cotton ball over the needle site as
the needle is removed.
- Put pressure on the site and then put on a
bandage.
How It Feels
Blood sample from a heel stick
A brief pain, like
a sting or a pinch, is usually felt when the lancet punctures the skin. Your
baby may feel a little discomfort with the skin puncture.
Blood sample from a vein
The blood sample is taken
from a vein in your arm. An elastic band is wrapped around your upper arm. It
may feel tight. You may feel nothing at all from the needle, or you may feel a
quick sting or pinch.
Risks
Heel stick
There is very little chance of a
problem from a heel stick. A small bruise may develop at the site.
Blood test
There is very little chance of a
problem from having a blood sample taken from a vein.
- You may get a small bruise at the site. You
can lower the chance of bruising by keeping pressure on the site for several
minutes.
- In rare cases, the vein may become swollen after the blood
sample is taken. This problem is called phlebitis. A warm compress can be used
several times a day to treat this.
- Ongoing bleeding can be a
problem for people with bleeding disorders. Aspirin, warfarin (Coumadin), and
other blood-thinning medicines can make bleeding more likely. If you have
bleeding or clotting problems, or if you take blood-thinning medicine, tell
your doctor before your blood sample is taken.
Results
This test measures the amount of lead in
the blood. Lead is a poisonous (toxic) metal that can damage the brain and
other parts of the body. A small amount is present in most people.
The normal values listed here—called a reference range—are just a guide. These ranges vary from lab to lab, and your lab may have a different range for what’s normal. Your lab report should contain the range your lab uses. Also, your doctor will evaluate your results based on your health and other factors. This means that a value that falls outside the normal values listed here may still be normal for you or your lab.
Results are usually available within 1 week.
If your blood test result is 10 mcg/dL or higher, your
doctor will want you to have another blood test. How soon you will be retested
is based on the results of your first test. If the result is only slightly
high, you may be retested in a month. If it is very high, your doctor may want
to repeat the test within a few days.
Levels of poisoning
There are five classes of lead levels, according to the United States Centers for Disease Control and
Prevention. These levels range from class 1 (no lead poisoning, or less
than 10 mcg/dL) to class 5 (a medical emergency of at least 70 mcg/dL).
Lead blood level classification| Class | Blood lead level | Possible effects in children |
|---|
1 | 1–9
mcg/dL or less than 0.48
mcmol/L | Learning problems |
2A | 10–14 mcg/dL or 0.48–0.68
mcmol/L | Hearing problems, slowed growth,
learning problems |
2B | 15–19 mcg/dL or 0.70–0.96
mcmol/L |
3 | 20–44 mcg/dL or 0.97–2.1 mcmol/L | Headache, weight loss, nervous system
problems |
4 | 45–69 mcg/dL or 2.17–3.33
mcmol/L | Severe stomach cramps, poor production of
red blood cells (anemia), seizures |
5 | More than 69 mcg/dL or more than 3.33
mcmol/L | Severe brain damage leading to
death |
What Affects the Test
You may not be able to
have the test or the results may not be helpful if your skin is contaminated with lead. Low levels of lead
can be found almost anywhere, including on the skin.
Having low iron levels in your blood may cause an increase in the absorption of lead.
What To Think About
- Blood tests for lead should be done by a lab
experienced in
proper technique. A finger stick or heel stick can
test for lead poisoning but must be done carefully to prevent contamination of
the sample from lead on the skin. Any result of 10 mcg/dL of lead or higher
from a finger or heel stick should be rechecked on a blood sample drawn from a
vein. Some doctors prefer to only test blood drawn from a vein. If the results
are too high, a follow-up blood sample should be taken from a vein to
double-check the results.
- Timed urine tests may be done to check the amount of lead in urine and/or to keep track of the amount of lead being removed from your body during treatment (chelation therapy).
- The U.S. Occupational Safety and Health Administration (OSHA)
requires companies to test the blood of employees who work with lead. Results
need to be reported to the local health department if 2 or more blood lead
levels are above 10 mcg/dL. A home inspection is needed to find the source of
the lead. For more information, see OSHA's Web site at www.osha.gov.
References
Other Works Consulted
- Committee on Environmental Health, American Academy of
Pediatrics (2005, reaffirmed 2009). Lead exposure in children: Prevention, detection, and
management. Pediatrics, 116: 1036–1046. Also available
online: http://www.pediatrics.org/cgi/content/full/116/4/1036.
- Fischbach FT, Dunning MB III, eds. (2009).
Manual of Laboratory and Diagnostic Tests, 8th ed.
Philadelphia: Lippincott Williams and Wilkins.
Credits
| By | Healthwise Staff |
|---|
| Primary Medical Reviewer | Susan C. Kim, MD - Pediatrics |
|---|
| Specialist Medical Reviewer | R. Steven Tharratt, MD, MPVM, FACP, FCCP - Pulmonology, Critical Care Medicine, Medical Toxicology |
|---|
| Last Revised | June 21, 2010 |
|---|
Seton is proud to have four hospitals – the only hospitals in Central Texas - that have earned the Magnet designation, the highest award for nursing excellence given by the American Nurses Association.