How Lead Poisoning Is Diagnosed

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Many doctors will routinely recommend screening kids for lead poisoning as early as 6 months, depending on how much lead the child is likely exposed to at home or in a childcare setting.

For older children and adults, testing is typically only done if there's a reason to believe they've been exposed to high doses of lead. In these cases, your doctor will likely start with a series of questions about your environment, do a physical exam, and run a blood test to check for high lead levels in the body.

lead poisoning diagnosis
Illustration by Joshua Seong. © Verywell, 2018.  

Self-Checks/At-Home Testing

Lead toxicity is primarily diagnosed using a formal lab test in a clinical setting, but there are a number of things you can do at home to check if you or a family member is at risk.

Lead is nearly everywhere in our environment, and high concentrations of it are found in things like old paint, solder, gasoline, soil, and contaminated water, as well as seemingly harmless items like some candy, artificial turf, toy jewelry, and alternative medicines.

The most dangerous source of lead for children, especially, is lead-based paint, which was often used in homes prior to the 1970s. The Environmental Protection Agency and Centers for Disease Control and Prevention both offer guidance on how to avoid common sources of lead.

In addition to removing or avoiding sources of lead in the home or at work, it's important to watch for signs of lead poisoning and alert your doctor right away if you see them—especially behavioral changes like irritability, hyperactivity, or lack of focus, as well as developmental delays in small children.

Screening 

No lead levels have been found to be safe in kids, and even small amounts have been linked to behavioral issues and drops in IQ.

Because of this, most pediatricians will routinely screen young children and infants for possible exposure to lead as part of their general checkups. In many cases, this includes a questionnaire asking about various risk factors, such as how old the child's home or daycare facility is, whether they eat non-food things like dirt or paint chips, or if a parent or close contact is exposed to lead frequently because of their job or hobbies. If the answer is yes or you aren't sure to any of the questions, your doctor will likely want to do more testing to check for elevated blood levels.

While research shows these questionnaires aren't great at identifying kids with high lead levels, they can help doctors and parents figure out where kids with diagnosed lead poisoning are being exposed to the heavy metal to prevent contact with it in the future. Pregnant and breastfeeding women are also generally asked a similar set of questions.

In many areas, the local health department will have specific recommendations on who should be tested for lead and when based on the area's trends and risks for high lead levels among locals. Generally speaking, however, it's recommended that all children be tested for high lead levels by ages 1 or 2, and children at higher risk for lead toxicity—such as those coming to the United States from a foreign country or babies born to moms with high blood lead levels—be tested as early as six months.

Physical Exam 

If there is any reason to suspect lead poisoning, your doctor will likely want to conduct a physical exam in addition to a blood test in order to look for signs and symptoms of toxicity.

This is important because as lead builds up in the body, it gets stored in the bones. It's only in the blood for a little while after exposure, meaning someone in contact with lead over a long period of time could have a high level of lead in their body even if a blood test comes back normal. A physical exam could catch signs a lab test couldn't.

Even so, because most cases of lead poisoning don't show any symptoms at all, a physical exam might not be enough to spot it. That's why blood tests are still a critical and primary tool used to diagnose lead toxicity.

Labs

The most common type of testing for lead poisoning is a blood test, known as the BLL (blood lead level) test. There are two kinds of blood tests that can indicate whether a person has an elevated blood lead level: a finger prick test and a blood draw.

Capillary Blood Sample

This method of testing uses only a finger prick to take a small sample of blood, making it a relatively simple and easy way to test for high lead levels. The downside, however, is that these samples can get contaminated with lead from the environment and skew test results to make it look like lead levels are higher than they really are.

You can reduce the risk of contamination by taking careful steps, like thorough hand-washing and other strategies, but a high lead level result will still need to be confirmed with a venous blood lead level test. For this reason, this method isn't often recommended, despite its convenience.

Venous Blood Lead Level Testing

A blood draw from a vein is a much more useful screening and diagnostic test for high lead levels, but requires a trained phlebotomist to take and process the sample to avoid contamination with lead from the environment. This method is often the preferred test to check for high lead levels because it tends to be more reliable than the finger prick test.

If a person has a blood lead level of 5 µg/dL (five micrograms per deciliter), they are considered to have an elevated blood lead level. If that happens, doctors will likely confirm the result with a second test anywhere from right away to 1 to 3 months, depending on the initial results.

If the test still comes back with high levels, the doctor will report it to the local health department and go over next steps with the family on what they can do to reduce the blood levels and stop the exposure to lead. In cases of very high lead levels (45 µg/dL or higher), advanced treatment might be needed, especially in kids. 

X-Ray 

In cases where children have symptoms of lead toxicity, elevated blood lead levels, and/or a history of pica—that is, eating non-food things like dirt or paint chips—it's recommended that an X-ray be taken of the abdomen to check for foreign objects. If solid flecks appear on the X-ray signaling the child has ingested materials containing lead, doctors will often use a decontamination procedure to irrigate, or "flush out," the intestines, removing the potential sources of lead to prevent or stop them from being absorbed by the body.

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