Specialty Testing Guide › Heavy Metals Testing
How do you read a heavy metals report? Check four things for each metal: the specimen (blood or urine), the unit, whether the urine result is adjusted for creatinine, and how the number compares with the reference range. Then read the result against your exposure history, because the same number can mean different things for different people.
Most importantly, a result flagged "above range" is not a diagnosis of poisoning. Reference ranges describe where most people fall, not where harm begins. A flag is a prompt to ask why, and sometimes to retest.
Key takeaways
- Reference ranges are drawn from population data, so a flag means unusual, not necessarily harmful.
- Urine results usually come adjusted for creatinine to account for how dilute the sample was.
- Seafood, a recent exposure or a chelating drug can each raise a result without signaling disease.
- A clinician weighs your exposure history and symptoms before acting on any single number.
Start with the specimen and the units
A report should say whether each metal was measured in blood or urine. That matters because the specimen decides what the number reflects. Blood lead, for example, is the standard measure of lead, while urine is the usual specimen for arsenic and inorganic mercury.
Units vary between labs, which causes a lot of confusion. Common ones are:
- µg/dL (micrograms per deciliter): used for blood lead in the United States.
- µg/L (micrograms per liter): used for blood mercury and many urine results. One µg/dL equals 10 µg/L.
- µg/g creatinine: a urine result adjusted for how concentrated the sample was.
Before you compare two reports from different labs, make sure the units and specimens match. A change from 3 to 30 may simply be a change from µg/dL to µg/L.
What creatinine correction does
A spot urine sample can be watery after you drink a lot, or concentrated first thing in the morning. Creatinine is a waste product released at a fairly steady rate, so labs divide the metal level by the creatinine level to even that out. CDC researchers found that urinary creatinine varies with age, sex, race and ethnicity, and body mass, so an adjusted result is best compared with a reference group like you.1
If a sample is extremely dilute or extremely concentrated, some labs flag it as unsuitable. In that case the honest step is to repeat the collection, not to interpret the number.
What the reference range means
Most metal reference ranges are statistical. They mark where the bulk of a healthy population falls. The adult blood lead reference value, for example, is 3.5 µg/dL, set to identify people above the 97.5th percentile of the population.2 It flags higher-than-usual exposure. It is not the line where symptoms start.
Some metals have separate action levels set for workplaces or by toxicologists, and those are often much higher than the lab's reference range. Your clinician should tell you which kind of line your result is being compared with.
No metal test predicts on its own whether you will get sick. The federal Agency for Toxic Substances and Disease Registry notes that mercury tests cannot predict whether you will have health problems.3 The same is true for other metals at low levels.
Why "above range" is not "poisoned"
Several things can push a result over the line without meaning harm:
- Seafood: fish and shellfish contain harmless organic arsenic that shows up in urine. In one clinic series, total urine arsenic averaged 291 µg/L before seafood avoidance and 9 µg/L after.4
- Many metals at once: the more metals a panel reports, the more likely one will fall outside its range by chance.
- A chelating drug: provoked urine results cannot be compared with normal reference values at all.
- Contamination: a container that is not metal-free, or dust during collection, can add metal to a sample.
Clinicians at an environmental medicine clinic have described patients with vague symptoms who came to believe they had metal toxicity from multi-metal panels, and noted the higher chance of false positives when many analytes are measured.5
What triggers a retest or more workup
A single mild flag with no exposure often calls for a repeat test, collected correctly, rather than treatment. More action is reasonable when:
- the result is well above the reference range, not just over it;
- you have a clear source, such as a job, hobby, well water or renovation;
- a repeat confirms the finding;
- you have symptoms or other lab changes that fit that metal.
When a result is confirmed, the first step is finding and removing the source. For arsenic, a high total is followed by speciation. For lead, follow-up is by blood lead at set intervals. In Pennsylvania, the Department of Health collects adult blood lead results of 5 µg/dL or greater to track sources of exposure.6
Next step
If you are planning a test, Preparing for a heavy metals test explains how to avoid the common false alarms above. The clinic's unprovoked test is an $89 add-on to an assessment, and a clinician reviews the report with you. More articles are on the heavy metals testing hub.
Frequently asked questions
My report says "detected." Is that bad?
Not necessarily. Modern labs can detect very small amounts, and most people have measurable levels of several metals from food, water and air. What matters is the amount, the form and the source.
Why does my urine report show two numbers for the same metal?
One is usually the raw concentration (per liter) and the other is adjusted for creatinine (per gram of creatinine). Ask your clinician which one the reference range applies to.
How soon should I retest?
It depends on the metal, the level and whether the source has been removed. Your clinician will set the timing; retesting too soon after removing a source can make it look as if nothing changed.
Should I start a binder or cleanse after a high result?
Not on your own. Confirm the result, find the source and talk with your clinician first. Evidence for over-the-counter products sold to remove metals is limited, and removing the exposure does far more.
Related reading
This article is for general education and is not medical advice. Decisions about testing and treatment should be made with your clinician. If you have severe symptoms, call 911. For a suspected poisoning, call Poison Control at 1-800-222-1222.
