Skip to content
Blood Test Tracker

Cadmium/Creatinine Ratio, Urine

Cadmium in a urine sample divided by the creatinine in the same sample. This evens out how watery the urine is and mainly reflects long-term exposure.

AI-verified against cited sources. Awaiting expert reviewAlso called Cd/Cr, CdU/CrLOINC 13471-8

Check your result

Sex (optional)

Type your result to see where it falls.

Nothing you type here leaves your browser.

What it is

Cadmium is a metal found in tobacco smoke, in some foods and in some workplaces. Your body holds on to it for decades, mostly in the kidneys, and a small amount leaves in the urine. Urine can be watery or concentrated, so labs also measure creatinine, a waste product that leaves at a fairly steady rate, and divide cadmium by it. The result is in micrograms of cadmium per gram of creatinine. This is the form of the test most often used to judge long-term exposure.

Why it matters

Long-term exposure to cadmium can strain the kidneys, and it is linked to weaker bones. This ratio is the usual way to track how much has built up over time, and it is the main number used in workplace monitoring. Most people have low levels. Smoking and some jobs are the common sources, and both can often be reduced.

If it’s high

A result above your lab's limit means more cadmium has built up in your body than is typical. It does not by itself show kidney damage. Most often the cause is smoking, food, or a job that involves cadmium. Your clinician can look at the number together with your kidney tests and your exposure history.

Common causes

  • Smoking tobacco (and, in survey data, smoking marijuana)
  • Everyday foods that naturally contain cadmium, such as grains, potatoes, leafy greens, shellfish and organ meats like liver and kidney
  • Low iron stores, which let the gut absorb more cadmium
  • Work with nickel-cadmium batteries, pigments, metal plating or smelting
  • Low urine creatinine from low muscle mass, which can push the ratio up
  • Kidney damage from long-term exposure, which lets more cadmium leak into the urine
  • A sample collected in a container that was not trace-element-free
  • A "provoked" test collected after a chelating medicine, which has no valid normal range

What can help

  • If you smoke, ask your clinician about support to quit
  • If you work with cadmium, ask your employer or occupational health team about protective equipment and monitoring
  • Ask about a kidney check, such as eGFR and urine protein, to put the number in context
  • Be wary of "provoked" or "challenge" urine tests; toxicology experts advise against them

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 0.6 µg/g creatinine. Source: Mayo Clinic Laboratories (catalog mirrored at testcatalog.org), ARUP Laboratories, ATSDR (Agency for Toxic Substances and Disease Registry), U.S. Occupational Safety and Health Administration.

What can affect your result

  • Smoking, diet, work and where you live
  • Age: cadmium builds up in the kidneys over a lifetime
  • Iron stores: low iron lets the gut absorb more cadmium
  • Muscle mass, age and sex, which change how much creatinine is in urine
  • Kidney function and kidney damage
  • Recent gadolinium or iodine contrast dye
  • Collection container and contamination
  • Very dilute or very concentrated urine can make the creatinine part of the ratio less reliable.
  • Creatinine itself varies with muscle mass, age, sex and diet, which can nudge the ratio.
  • Contrast dye can interfere with this kind of metal test. Mayo advises waiting 96 hours after gadolinium or iodine contrast. ARUP advises avoiding iodine-containing medicines or contrast agents for at least 1 month before urine metal testing.
  • Use the trace-element-free plastic container your lab provides. A container that is not trace-element-free can add cadmium.
  • Urine collected after taking a chelating medicine (a "provoked" test) cannot be compared with a normal range.

A single (random) urine sample. Mayo does not ask for a particular time of day. For workplace monitoring, ARUP asks for collection at the start of the work shift to avoid contamination. Changes slowly. Urine cadmium mostly reflects exposure built up over years, so it will not fall quickly after exposure stops (the whole-body half-time is about 20 to 30 years).

When to talk to a clinician

Talk with your clinician if your result is above your lab's limit, and sooner if you work with cadmium. For workers, OSHA's standard calls for a review of workplace exposure when a worker's result is above 3 µg/g creatinine, with a higher trigger above 15 µg/g. Get medical care right away if you breathed in fumes or dust from heated or welded cadmium-containing metal and now have cough, chest tightness, shortness of breath or fever. If you may have swallowed a large amount, call Poison Control (1-800-222-1222 in the US). Lab limits for this test are not emergency thresholds.

Questions you could ask

  • If my exposure continues, how often should this be rechecked?
  • Could smoking, my diet or my job explain this result?
  • Should we check my kidneys, for example eGFR and urine protein?
  • Should we repeat the sample, or also check blood cadmium?

Questions people ask

Why does my lab's limit differ from another lab's?

Labs set their own limits and some tie them to workplace safety rather than to the general public. Mayo prints under 0.6 µg/g creatinine for adults, while ARUP prints 3.2 or lower. In US government survey tables (NHANES), about 95 in 100 adults were below roughly 1 µg/g. The range on your own report is the one to compare with.

Can I convert this to the per-liter result?

Not without a creatinine value from the same urine sample. That is why the per-liter and per-gram-of-creatinine results are separate markers.

Does a high result mean my kidneys are damaged?

Not by itself. A high result means more cadmium has built up than is typical. Kidney effects in studies appear mostly at higher levels and after years of exposure. Your clinician can check your kidneys with simple blood and urine tests.

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 Cadmium/Creat (Urine) unit converter

For clinicians and researchers

Urine cadmium divided by urine creatinine, with cadmium by ICP-MS or ICP-MS/MS and creatinine by an enzymatic or colorimetric method. Urine cadmium primarily reflects total body burden and correlates better with kidney cadmium than blood does. In an autopsy study, 1.7 µg/g creatinine corresponded to a renal cortex level of about 50 µg/g. ATSDR's draft profile reports an adult US geometric mean of about 0.19 µg/g creatinine (CDC 2024), and its NHANES tables put the adult 95th percentile at about 1 µg/g creatinine across survey cycles. Early kidney effects are described at about 2 µg/g creatinine (biochemical changes), about 4 µg/g (higher-molecular-weight proteins and enzymes) and about 10 µg/g (low-molecular-weight proteins). A meta-analysis found a benchmark dose lower limit of about 2.0 µg/g creatinine for the tubular marker NAG. Associations with lower GFR have been seen in groups with mean urine cadmium of 4 to 6 µg/g creatinine but mostly not at 1 µg/g or less. In a worker study, increased tubular proteinuria was often seen with urine cadmium above 10 µg/g, and when beta-2-microglobulin stayed at or below 300 µg/g after exposure was reduced, later tubular damage was judged unlikely. OSHA's cadmium standard (29 CFR 1910.1027) uses 3 µg/g creatinine as the initial and continuing level, 15 µg/g as the higher trigger, and 7 µg/g in the alternative post-1999 scheme, together with blood cadmium and urine beta-2-microglobulin. Mayo's general reference (under 0.6 µg/g, adults) is tighter than ARUP's (3.2 µg/g), so the same result can be flagged by one lab and not another. Creatinine correction assumes steady creatinine excretion, which varies with muscle mass, age, sex and diet. IARC classifies cadmium as carcinogenic to humans (Group 1).

LOINC 13471-8 (primary), 56651-3, 22696-9, 13828-9. Specimen: urine.

Sources

  1. Cadmium/Creatinine Ratio, Random, Urine (Mayo test CDUCR), Mayo Clinic Laboratories (catalog mirrored at testcatalog.org)
  2. Cadmium Occupational Exposure, Random, Urine (Mayo test CDUOE), Mayo Clinic Laboratories (catalog mirrored at testcatalog.org)
  3. Cadmium, Urine (ARUP test code 0025040), ARUP Laboratories
  4. Cadmium Exposure Panel - OSHA (ARUP test code 0025013), ARUP Laboratories
  5. Toxicological Profile for Cadmium (Draft for Public Comment), Chapter 3: Toxicokinetics, Susceptible Populations, Biomarkers, Chemical Interactions, ATSDR (Agency for Toxic Substances and Disease Registry) (2025)
  6. Toxicological Profile for Cadmium (Draft for Public Comment), Chapter 5: Potential for Human Exposure, ATSDR (Agency for Toxic Substances and Disease Registry) (2025)
  7. Toxicological Profile for Cadmium (Draft for Public Comment), Chapter 2: Health Effects, ATSDR (Agency for Toxic Substances and Disease Registry) (2025)
  8. 29 CFR 1910.1027, Cadmium (medical surveillance: biological monitoring levels), U.S. Occupational Safety and Health Administration
  9. Recommendations for provoked challenge urine testing, Journal of Medical Toxicology (2013)
  10. Creatinine (PubChem compound 588), 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.

Related markers