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Lead/Creatinine Ratio, Urine

Lead in a urine sample, shown per gram of creatinine so the result is not thrown off by how dilute your urine is.

AI-verified against cited sources. Awaiting expert reviewAlso called Pb/CrLOINC 13466-8

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What it is

Lead is a metal that can get into the body from lead paint and dust, soil, old water pipes, some jobs and some hobbies. This test measures how much lead leaves your body in urine. A single urine sample can be watery or concentrated, so the lab also measures creatinine, a waste product your body makes at a steady rate, and reports lead per gram of creatinine to even that out.

Why it matters

Lead can affect the nerves, kidneys, blood and blood pressure, and children are especially sensitive to it. Blood lead is the standard test for checking lead exposure. A urine test can add information about recent exposure, and it is sometimes used for workplace monitoring.

If it’s high

A higher result means more lead is passing into your urine. That can happen with recent or ongoing contact with lead, but it can also come from a contaminated sample. The number alone can't tell how much lead is stored in your body.

Common causes

  • A contaminated sample (dust, skin or a container that was not trace-element-free)
  • Lead paint dust or soil at home, especially in older housing or during renovation
  • Work with lead, such as battery, smelting, ammunition, construction or demolition work
  • Hobbies that involve lead, such as stained glass, casting or shooting at an indoor range
  • Old plumbing, some imported pottery, cosmetics or traditional remedies that contain lead
  • A sample collected after a chelating medicine

What can help

  • Ask your clinician whether a venous blood lead test should be added, since it is the standard test
  • Ask whether to repeat the urine test in a certified trace-element-free container
  • Look into possible sources at home, at work and in hobbies, and ask about workplace monitoring
  • Follow local public-health guidance if lead paint or water pipes may be a source

Usual ranges

What labs print as the reference range, by who was tested. Ranges differ a little between labs, so the range on your own report is the one your result is judged against.

For adults: up to 2 µg/g creatinine. Source: Mayo Clinic Laboratories (via the testcatalog.org mirror), ARUP Laboratories.

What can affect your result

  • How dilute or concentrated your urine is, which the creatinine correction tries to even out
  • Recent contrast dye (gadolinium or iodine) before the collection
  • The collection container and how the sample was handled
  • Kidney function, which changes how much lead and creatinine reach the urine
  • A chelating medicine given before the sample, which makes urine lead jump for a short time
  • Gadolinium or iodine contrast dye can interfere with this kind of metal test. Mayo Clinic Laboratories asks for a 96-hour wait after contrast, and ARUP asks for at least 72 hours (14 days if kidney function is reduced).
  • A sample contaminated by skin, dust or a container that is not certified trace-element-free can read falsely high. Labs may ask for a repeat in a certified container.
  • Urine collected after a chelating (metal-binding) medicine, called a provoked or challenge test, has no valid reference range.
  • A single (spot) urine sample can vary a lot through the day, which is why the lead result is divided by creatinine.

Weeks. Lead in blood has a half-life of about 40 days in adult men, and lead stored in bone can keep releasing for years.

When to talk to a clinician

Contact your clinician soon if your result is above your lab's range, especially if you work with lead, live in an older home that is being renovated, are pregnant or have young children at home. Seek urgent care for severe belly pain, confusion, seizures or new weakness after a known heavy lead exposure.

Questions you could ask

  • Is a urine test or a blood test the better fit for my situation?
  • Should we also check a blood lead level?
  • Could my home, job or hobbies be a source of lead?
  • Should we repeat this test in a certified trace-element-free container?

Questions people ask

Is a urine lead test the best way to check for lead?

Usually not. Blood lead is the standard test, and the CDC recommends venous blood for lead testing. ARUP Laboratories suggests urine mainly for chronic exposure or to monitor treatment with a chelating medicine.

Why is my result shown per gram of creatinine?

Urine can be more watery or more concentrated from one sample to the next. Creatinine is released at a steady rate, so dividing lead by creatinine makes samples easier to compare.

What is a provoked or challenge urine lead test?

It is a urine test collected after taking a chelating medicine. Normal ranges don't apply to those samples, and the American College of Medical Toxicology recommends against using them. Talk with your clinician if one was suggested to you.

Show the science and sources

Units

  • 1 µg/g creatinine = 1 µg/g creatinine
  • 1 µg/g creatinine = 0.1131 µg/mmol creatinine

Open the Urine Lead/Creatinine unit converter

For clinicians and researchers

Random urine, measured by triple-quadrupole ICP-MS (Mayo Clinic Laboratories PBUCR) with creatinine measured on the same sample by an enzymatic colorimetric assay. Urine lead is filtered from plasma lead, so it tracks recent plasma lead more than total body burden. Spot samples vary widely, which is why creatinine correction is needed (Barbosa 2005). Blood lead has a mean half-life of about 40 days in adult men, while bone lead has a half-life of 10 to 30 years, so urine and blood results can miss long-term stores. Blood lead is the preferred routine test: Mayo notes the CDC recommends venous blood for lead testing, and ARUP prefers blood for routine testing and suggests urine for chronic exposure or chelation monitoring. Reference limits differ by lab (Mayo below 2 µg/g creatinine in adults; ARUP up to 5.0 µg/g). Post-chelator challenge urine testing has no valid reference range, and the American College of Medical Toxicology recommends against it. Creatinine correction is less reliable in very dilute or very concentrated urine.

LOINC 13466-8 (primary), 34327-7. Specimen: urine.

Sources

  1. Lead/Creatinine Ratio, Random, Urine (test PBUCR), Mayo Clinic Laboratories (via the testcatalog.org mirror)
  2. Lead, Random Urine (test 2011482), ARUP Laboratories
  3. A critical review of biomarkers used for monitoring human exposure to lead: advantages, limitations, and future needs, Environmental Health Perspectives (2005)
  4. ACMT Recommends Against Use of Post-Chelator Challenge Urinary Metal Testing, American College of Medical Toxicology (Journal of Medical Toxicology) (2017)
  5. Creatinine (compound summary), PubChem, National Library of Medicine

AI-verified against cited sources. Awaiting expert review. Last reviewed 2026-10-03. How we build and check these pages.

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