Episode Transcript
Hi and Welcome to Clerkship Ready - Pediatrics - A podcast aimed at helping you excel during your clinical clerkship in Pediatrics.
I’m Dr. Rachel Moon, and I am a Professor of Pediatrics at the University of Virginia School of Medicine. Today we’re going to talk about what you need to know before you order lead testing for your patient. We’re going to talk about what lead is, sources of lead exposure, why lead exposure is a problem, signs and symptoms of lead toxicity, how to screen for lead toxicity, and what to do if your patient has an elevated lead level.
Let’s start by talking about what lead is and WHERE lead is.
Lead is a naturally occurring metal that is commonly found in the environment. The primary ways for lead to enter the body are through ingestion of contaminated food or water, and/or ingestion or breathing in of lead dust. Other sources of lead exposure are lead-acid batteries for motor vehicles, ammunition, lead-based pigments and paints, stained glass, lead crystal glasses, ceramic glazes, jewelry, and toys. So when we screen for lead risk, we may ask questions about whether family members work with batteries, smelting, or near airports, since airplane fuel is leaded, if they renovate homes or buildings, or have hobbies, such as painting, jewelry or stained glass making. If family members are exposed to lead, it can be on their skin or clothes, and children can become exposed. If you see patients from other cultures, you also need to consider that ceramic glazes used to make dishes, some traditional cosmetics such as kohl and sindoor, and some traditional medicines often contain lead.
Because lead exposure at any level can cause negative health effects, there have been a lot of US government policies in recent years that have decreased exposure to lead. These include the switch to unleaded gasoline for cars, lead-free paints, lead-free solder in food cans, and lead-free water pipes. You may remember hearing about the Flint Michigan water crisis, which was discovered by a pediatrician, Dr. Mona Hanna-Attisha, who noticed that an unexpectedly high proportion of her patients had elevated lead levels. It turned out that the water supply for Flint had been changed to the Flint River. The water was inadequately treated, and the contaminated water caused corrosion in old lead water pipes and leaching of lead into the water. Dr. Hanna-Attisha wrote a book about her experiences, entitled What the Eyes Don’t See. I’ve put that link in the show notes.
Why do we worry about lead?
Lead toxicity, or poisoning, occurs when lead builds up in the body, often over months or years. It accumulates in the brain, kidneys, liver, teeth and bones. Even small amounts of lead can cause serious health problems. In adults, it can cause high blood pressure, cardiovascular problems and kidney damage. Exposure of pregnant women to high levels of lead can cause miscarriage, stillbirth, premature birth and low birth weight.
However, children, particularly those younger than 6 years, are at the highest risk for lead exposure. First of all, they are more likely to be exposed due to their hand-to-mouth behavior. Many children ingest lead dust by putting objects such as toys and dirt in their mouths. Secondly, young children absorb 4-5 times as much ingested lead as adults. Finally, the developing nervous system is particularly vulnerable to damage from lead. Children are even more susceptible to lead toxicity if they are undernourished – particularly if they are deficient in calcium or iron, because there is more absorption of lead into the body.
Lead toxicity can cause permanent damage -in particular, to the brain and nervous system, resulting in delays in growth and development, lower IQ, learning and behavior problems, hearing and speech problems, and school underperformance.
Initially, lead poisoning can be hard to detect by history and physical, because signs and symptoms usually don’t appear until lead levels are very high – like >50 µg/dL. However, given that levels as low as 3.5 µg/dL have been associated with decreased intelligence, behavioral difficulties and learning problems, we have to depend upon blood lead testing for children who are at high risk. We’ll talk about that in a few minutes.
When there are signs and symptoms of lead toxicity in children, you might see:
Developmental delay or learning difficulties
Irritability
Loss of appetite
Weight loss
Sluggishness and fatigue
Abdominal pain, vomiting, and/or constipation
Hearing loss
Anemia
You may also see pica – or eating non-food items, such as paint chips or toilet paper
Extremely high levels of lead - >100 µg/dL - can cause seizures, coma, and death.
Now that we’ve talked about all of this scary stuff, let’s talk about prevention. As I mentioned, there have been a lot of policy changes on state and national levels that have resulted in many fewer children having high lead levels. But the other big piece of prevention is screening, because any lead in the body can cause problems.
So we screen all children at ages 1 and 2 years.
In some places, particularly where lead risk is low, clinicians may use screening questionnaires to decide who gets blood lead testing. However, these screening questionnaires are not good at figuring out who doesn’t need lead testing, but they may be helpful in identifying lead hazards for those who end up having elevated blood lead levels.
These screening questionnaires include questions such as:
Does this child live in or regularly visit a home that was built before 1978? 1978 is when lead-based paints were banned, so homes built before then probably contain lead-based paint. If the house is well maintained without peeling or cracked paint, it should be ok. However, when the paint peels and cracks, it makes lead dust, particularly around windows when they are open and shut.
Does this child live with someone who has a job or a hobby that may involve lead (for example, jewelry making, building renovation or repair, bridge construction, plumbing, furniture refinishing, or work with automobile batteries or radiators, lead solder, leaded glass, lead shots, bullets or lead fishing sinkers)?
Has this child ever been to Mexico, Central or South America, Asian countries (i.e., China or India), or any country where exposure to lead from certain items could have occurred (for example, cosmetics, home remedies, folk medicines or glazed pottery)?
However, most clinicians will screen for lead by doing a blood lead test – and this is what the AAP and CDC recommend. Of note, children enrolled in Medicaid insurance are required to have blood lead tests at 12 and 24 months of age, or between 24–72 months of age if they have no record of ever being tested. And many child care centers, preschools, and elementary schools require at least one blood lead test at or after the age of 24 months.
There are 2 ways to get a blood sample for lead testing. Check with your practice to see how they do it.
The first way is a capillary sample, obtained by finger-prick or heel-prick. This sample is then used for what is called a point-of-care tests\, which can be easily done in the office, and the results are available before the end of the visit. However, if the finger is not cleaned well, lead on the skin may result in a higher lead level that needs to be confirmed by a venous sample.
The second way is a venous blood draw. There is less likely to be lead contamination this way. However, it generally has to be sent to a lab, and it may take a few days to get the results back.
What do you do if the lead level is high?
If the lead level is high – meaning 3.5 µg/dL or higher, first check to see if it was a capillary sample. If it was, then you need to repeat a venous sample to confirm that the level is actually high. The higher the level, the more urgent it is to repeat the sample. For instance, if the level is <10, it’s fine to check it within 1-3 months. If the level is >45, you need to recheck it within 48 hours. On the CDC website and the AAP policy statement, there are tables that tell you how urgently you need to get the confirmatory venous level. (you’ll find both links in the show notes)
Let’s say that you’ve confirmed the lead level, and it’s still high. Now what should you do? That depends on how high the level is. We’ll talk briefly about management, but you should review the detailed recommendations from the AAP and CDC whenever you have a patient with an elevated lead level.
If the level is between 3.5 and 5, you need to review the results with the family. Ask about common sources of environmental lead exposure, as we’ve discussed on this episode. Ask about nutrition and development, and assess any risk factors for iron deficiency, such as excessive cow milk intake or a limited diet, or calcium deficiency. Ask about developmental milestones, and if you’re concerned, you may need to refer the patient to early intervention services. If you’re worried about continued exposure, then you will want to repeat the lead in 6-12 months to make sure it’s not rising. If the child’s exposure to lead stops, the blood level will gradually decrease as the lead is excreted in urine and feces.
If the level is higher than 5, you will want to repeat the lead sooner – so 2-3 months- to make sure it’s not rising. Often the health department needs to be notified at this point – so that they can send someone to the home to test for lead. Families can also independently hire a certified lead inspector to test for lead or, if they are renting, ask their landlord to have the home inspected.
If the level is above 15, particularly if the child has a history of pica, in addition to everything that we’ve already discussed, you may want to get an abdominal xray to look for lead paint chips or foreign bodies. If the level is above 45, outpatient or inpatient chelation treatment may be needed.
This is a lot of remember – so be sure to look it up if you have a patient with an elevated lead level, so that you are following all of the treatment guidelines!
And that’s it. I hope that you now know why we worry about lead exposure, what to ask parents about if you’re worried about lead exposure, how to screen for it, and what to do if your patient has an elevated lead level. Fortunately, lead toxicity is a preventable problem, and with all of the policies that have been implemented in the past few decades, has become much less common. However, you still need to be alert to the potential for it in your patients.
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