Also known as:Blood Lead Test; Blood Lead Level; BLL
Formal name:Lead, blood
Related tests:Zinc Protoporphyrin; Heavy Metals
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Why Get Tested?
To screen for possible excessive exposure to lead
When to Get Tested?
As indicated by a child lead screening program or physician preference, such as at 1 and 2 years of age; children considered to be at risk may need additional testing from 18 months to 6 years of age; when your occupation or hobby may expose you or your family to lead; when you have symptoms suggesting lead poisoning
A blood sample taken from a vein in your arm or by fingerstick or heelstick (for infants)
Test Preparation Needed?
How is it used?
The lead test is used to determine the concentration of lead in the blood at the time the sample was collected. The blood lead test is used to screen for exposure to lead. It may also be ordered to monitor the effectiveness of treatment and to confirm that lead levels are decreasing over time.
Lead concentrations are monitored at the local level following state and national standards. The Centers for Disease Control and Prevention (CDC), the American Academy of Pediatrics (AAP), and a variety of other organizations make recommendations regarding screening children for lead exposure. Testing recommendations and the definition of what is an abnormal blood lead level have changed significantly over the past 45 years.
The CDC uses a threshold blood lead level (BLL) of 5 mcg/dL to identify children living in environments that expose them to lead hazards. Children with elevated blood lead levels should prompt responses that include environmental assessments to determine lead sources, educating family members about Lead Poisoning, and instituting follow-up testing to monitor the condition. Children should also be assessed for iron deficiency and general nutrition consistent with AAP guidelines. BLLs will need to be monitored over time until the environmental investigations and subsequent responses are complete. Children with BLLs greater than 45 mcg/dL need evaluation and treatment (chelation).
Blood lead is monitored in workers whose environment contains lead. It is used to evaluate chronic lead exposure and recent lead exposure. Sometimes, a zinc protoporphyrin (ZPP) test is also ordered. The ZPP is increased when lead begins to affect red blood cell production. It is not sensitive enough to use as a screening tool for children, but it may be ordered to help evaluate average lead exposure in adults over the last several weeks.
When is it ordered?
For screening children:
The American Academy of Pediatrics (AAP) recommends that a risk assessment be performed for lead exposure at well-child visits at 6 months, 9 months, 12 months, 18 months, 24 months, and at 3, 4, 5, and 6 years of age. A blood lead level test should be done only if the risk assessment comes back positive. According to the AAP and the U.S. Centers for Disease Control and Prevention (CDC), universal screening or blood lead level tests are no longer recommended, except for children in high prevalence areas with increased risk factors.
Pediatricians may also offer screening to:
- Medicaid-eligible children at age 1 and again at 2 years of age
- Children of all ages who are recent immigrants, refugees, or adoptees at the earliest opportunity
- A child whose parent, guardian, or provider requests blood lead testing due to suspected exposure
People should check with their healthcare practitioner and/or local health department regarding lead screening guidelines specific to the risks in their area.
Managing children with elevated blood levels:
Since fingerstick samples can be contaminated during collection of the specimen, an initial elevated result obtained by a fingerstick sample should be repeated with testing on a blood sample drawn from a vein in the arm for confirmation, usually within a week to a month after the first test. Follow-up testing is then used to monitor the persistence of an elevated blood lead test and is recommended whenever a child's blood lead level is higher than 5 mcg/dL. Those with persistent lead levels above 5-19 mcg/dL (remain elevated for 3 months or more) and those with initial tests greater than 20 mcg/dL should have their home surroundings evaluated to determine the source of the lead exposure.
For screening adults:
Blood lead tests may be ordered to screen adults in the workplace when lead contamination is a possibility. Family members also may be screened because lead can be carried home on clothing. This testing conforms to federal and state laws for occupational exposure.
There is not yet a national guideline for blood lead screening in adults as there is for children. The clinical cut-off values for elevated blood lead currently vary from state to state. According to the CDC's Adult Blood Lead Surveillance program (ABLES), a national health objective is to reduce all blood levels in adults to less than or equal to 5 mcg/dL in 2015.
Adults who work in industries known for lead exposure, such as smelter facilities, lead plating, auto repair, and construction, should be screened for lead exposure. Adults who have hobbies that involve lead-based paints, ceramics, or gasoline also should be tested. For a list of hobbies that may expose someone to potentially high levels of lead, see the article on lead poisoning.
The Occupational Safety and Health Administration (OSHA) has developed rules for monitoring for lead in the workplace. OSHA requires that employee blood monitoring programs be triggered by the results found in an initial air monitoring program. If a worker has an initial blood lead test result of more than 40 mcg/dL, for example, testing should be done every two months until two consecutive lead tests show a blood lead level below 40 mcg/dL. Higher levels call for closer monitoring.
For both children and adults, lead testing may be ordered when a person's symptoms suggest potential lead poisoning. These symptoms are non-specific and may include fatigue, changes in mood, nausea, prolonged stomach distress, headache, tremors, weight loss, peripheral neuropathy, anemia, reproductive failure, encephalopathy, memory loss, seizures, and coma. Many children have no physical symptoms at the time of the exposure, but potentially permanent damage can still be occurring. Testing for lead exposure should be considered in children presenting with growth failure, anemia, sleep problems, hearing loss, or speech, language or attention deficits.
What does the test result mean?
The higher the test result, the more lead is in the blood. However, the amount of lead in the blood does not necessarily reflect the total amount of lead in the body. This is because lead travels from the lungs and intestinal tract to the blood and organs, and then is gradually removed from the blood and organs and stored in tissues such as bones and teeth. The danger that a particular lead level represents depends on the age and health of the person, the amount of lead they are exposed to, and the amount of time that they are exposed to elevated lead levels.
Exposure to lead is not healthy for anyone, but children are more vulnerable to its effects. The CDC uses a threshold blood lead level (BLL) of 5 mcg/dL (five micrograms per deciliter) to identify children living in environments that expose them to lead hazards. Any test results above this level should trigger lead management and monitoring. Any child who has an elevated blood lead level needs to have his or her home or other environment evaluated. Other people at the residence should be tested as well. Without the elimination or reduction of the source of the exposure - a lead hazard in the environment - the elevated lead level will likely recur.
In 2015, the National Institute of Occupational Safety and Health (NIOSH) designated 5 mcg/dL as an elevated blood lead level in adults. The U.S. Department of Health and Human Services recommends that blood lead levels among all adults be reduced to less than 10 mcg/dL. The U.S. Occupational Safety and Health Administration (OSHA) Lead Standards require workers to be removed from lead exposure when BLLs are greater than or equal to 50 mcg/dL (construction industry) or greater than or equal to 60 mcg/dL in general industry, and allow workers to return to work when their BLL is less than 40 mcg/dL. Removal may also be recommended if the person is symptomatic at any level below 70 mcg/dL.
Because lead will pass through the blood to an unborn child, pregnant women need to limit their exposure to lead to maintain a low blood level and as close to zero as possible to protect the developing fetus.
Most experts agree that a child with a lead level greater than 45 mcg/dL should be treated with succimer/chelator in the hospital unless he or she is encephalopathic. Any lead level greater than 70 mcg/dL, whether in a child or an adult, should be considered a medical emergency.
Is there anything else I should know?
Poisoning with lead is more harmful for children, whose brains and other organs are still developing. Adults tend to recover from lead ingestion better than children. Children who may be at risk should be screened as soon as possible.
Lead interferes with the absorption of iron. Children with raised blood lead concentrations should be tested for iron deficiency.
Each person eliminates lead differently. Thus, laboratory tests are just one part of the picture in lead poisoning cases. Careful monitoring with medical examinations is needed.
Healthcare practitioners should be aware that cultural practices and folk remedies, including soil ingestion, can increase a person's risk of lead exposure. Folk remedies prepared by newly immigrated populations from Southeast Asia are particularly known as possible sources of lead. Other potential lead sources include imported foods, candy, cosmetics, costume jewelry, brass keys, and toys or household items containing or painted with lead.
What is being tested?
Lead is a soft metal present in the environment. When it is inhaled or ingested, lead can cause damage to the brain, organs, and nervous system. This test measures the current lead level in the blood.
Even at low levels, lead can cause irreversible damage without causing physical symptoms. In an infant, lead can cause permanent cognitive impairment, behavioral disorders, and developmental delays. Lead exposure can cause weakness, anemia, nausea, weight loss, fatigue, headaches, stomach pain, and kidney, nervous system, and reproductive dysfunction. Lead can be passed from mothers to their unborn children and can cause miscarriages and premature births.
In the past, lead was used in paints, gasoline, water pipes, and other household products, such as the solder used in canned food. Although these uses have been limited in the U.S., lead is still used in many products and industrial processes both in the U.S. and around the world. Housing built prior to 1978 may contain lead-based paint and lead-contaminated household dust. Soil surrounding these houses may also be contaminated with lead.
Children under 6 years of age are the most likely to be exposed to lead because they often put their hands in their mouths, accidentally ingesting lead dust or paint chips. They can also inhale lead dust and mouth or chew lead-contaminated items. Adult lead exposure is usually related to occupational or recreational (hobby) exposure. Children of those who work with lead may also become exposed when lead contamination is brought home on the work clothes of their parents.
For additional information, read the article on Lead Poisoning.
How is the sample collected for testing?
Blood is drawn from a vein in the arm. Sometimes, blood is collected by fingerstick (or heelstick for infants). If test results from a fingerstick are abnormal, a venous blood draw should be ordered to confirm the results.
NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
Is any test preparation needed to ensure the quality of the sample?
No test preparation is needed.
- What products in the U.S. still contain lead, besides paint and ceramics?
Some products that still contain lead include car batteries, solder, some pipes, ammunition, roofing, industrial paints, job sites, hobby areas, electronics, batteries, scrap metal recycling, some PVC, vinyl and plastics, brass objects including keys, costume jewelry, and X-ray shield materials.
- How do people get exposed? Is touching these products enough to raise my blood level?
Just holding a lead object in your hands won't poison you. Most lead is present as an inorganic compound and does not move well through the skin. Breathing in or swallowing lead-laden dust may poison you, however. Situations that could lead to lead poisoning would be:
- Touching surfaces covered with lead dust and then transferring the dust to your mouth with fingers, food, or toys
- A toddler touching the windowsills in a pre-1978 house with their mouth or fingers and then swallowing lead dust or lead chips
- Inhaling dust during a home renovation project on a house built before 1978, especially when using power sanders or other work practices that generate lead-contaminated dust
- Ingesting lead through gardening in contaminated soil around the foundation of an older house or garage, or in soil contaminated with leaded gas along older highways, or abandoned industrial settings
- Drinking water through lead pipes - this is more common on the East Coast of the U.S.
- Swallowing lead shot (shotgun ammunition), a curtain weight, or a lead toy and not passing it through your system
- Inhaling fumes from burning lead-painted wood or battery casings in home fireplaces
- Consumer products:
- Baby bibs, electrical cords, purses, garden hoses
- Toys, art supplies, imitation leather, jewelery, hair dyes
- Brass faucets, fishery sinkers, curtain weights
- What occupations might result in lead exposure?
Some occupations that put people and their families at risk for lead exposure include:
- Lead smelting
- Steel welding
- Bridge reconstruction
- Firing range instruction and cleaners
- Remodeling and refinishing older homes
- Foundry work
- Scrap metal recycling
- Stained glass making
- Using lead glazes in ceramics
- Painting metal
- Auto repair work
- Electrician work
- Cable splicing
- Are there ways to protect myself and my family from getting lead exposure?
Yes. If your home was built before 1978:
- Assume that you may have lead in the house, or get the house and the soil that surrounds it checked by a professional
- Use cold water for drinking
- Damp mop smooth floors and surfaces frequently to control dust
- Vacuum carpets and upholstery to remove dust - use a HEPA vacuum filter if possible
- Do a monthly check to look for chipping, peeling, or other damaged surfaces, especially in window areas and porches; repair any chipping, peeling, or damaged paint or surface as soon as it is observed, then thoroughly clean the area to remove lead dust
- Learn how to do renovation and repair projects using lead-safe work practices to avoid creating more lead dust or contamination
For your child:
- Frequently wash your child's hands and toys to reduce lead dust contamination
- Avoid using home remedies that contain lead
- Keep your children (and pregnant women) away from lead hazards and out of the area during renovation or repair projects
- Don't let children put objects in their mouths that were not made to be used as a child's toy, including keys, jewelry, or dirt
- Get your child tested for lead at least at 1 and 2 years of age; contact your local health department to learn more about screening recommendations for your area
- Eat a well-balanced diet with adequate calcium, iron, and vitamin C
- Are there ways to protect myself and my family from getting lead exposure if I work in a dangerous area?
Yes. If you are working in a potentially harmful environment with exposure to lead dust or fumes:
- Wash your hands before you eat, drink, or smoke
- Eat, drink, and smoke in areas that are free from lead dust and fumes
- Wear a properly fitted respirator with a HEPA filter (N-100 rating); shave your face to get the best fit
- Keep your street clothes in a clean place; change into different clothes and shoes before you work with lead
- Shower immediately after working with lead, before you go home
- Launder your work clothes at the work place or separately from other family members' clothes
- How can I find out if my workplace is dangerous?
For more information about lead poisoning and workplace safety, visit the National Center for Environmental Health online at http://www.cdc.gov/nceh. For state and local health department assistance, you can contact CDC Emergency Response (24-hr. assistance during emergencies only) at 770-488-7100.
© 2017 American Association for Clinical Chemistry, republished from Lab Tests Online.*
Descriptions of clinical laboratory tests were originally prepared for use on Lab Tests Online, an award-winning patient education website on clinical laboratory testing. Lab Tests Online is produced by the American Association for Clinical Chemistry (AACC), a global scientific and medical professional organization dedicated to clinical laboratory science and its application to healthcare. The Lab Tests Online website is developed in collaboration with other laboratory professional societies and is funded in part through corporate sponsorships.