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Blood Test Tracker

Cadmium, 24-Hour Urine

Measures the cadmium that left your body in urine over a full day, a main test for long-term exposure to this metal.

AI-verified against cited sources. Awaiting expert reviewLOINC 5612-7

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What it is

Cadmium is a metal used in batteries, pigments and some plastics. It is also found in tobacco smoke and in small amounts in many foods. Your body absorbs a little and holds on to it for many years, mostly in the kidneys. It leaves very slowly through the urine. This test measures the cadmium in all the urine you collect over 24 hours. Because it changes slowly, it shows long-term exposure rather than what you ate or breathed today.

Why it matters

Cadmium builds up in the kidneys over the years. With heavy long-term exposure it can harm the kidneys and weaken the bones, and it is also linked to some cancers. Urine cadmium is the main test for long-term exposure. A result tells you about exposure, not whether you will have health problems. Your clinician reads it together with your smoking history, job and kidney tests.

If it’s high

A result above your lab's limit means more cadmium than usual is leaving your body. This usually reflects exposure over months to years. Smoking is a very common reason. Diet and some workplaces can also raise it. If cadmium has already affected the kidneys, urine levels can rise sharply and then no longer match the total built up in the body. Your clinician can put the number in context.

Common causes

  • Smoking, or living with someone who smokes
  • Diet: leafy greens, potatoes, grains, peanuts, soybeans, sunflower seeds, shellfish and organ meats can contain cadmium
  • Work that makes or uses cadmium, such as in batteries, pigments or metal alloys
  • Living near a factory that makes or uses cadmium
  • Older age, because cadmium builds up over time

What can help

  • If you smoke, ask your clinician about support to quit, and how to limit secondhand smoke
  • If you work with cadmium, ask about workplace protection and monitoring
  • Ask your clinician whether kidney tests, such as creatinine, eGFR and urine protein, make sense alongside this result

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 0.7 µg/24 h. Source: Mayo Clinic Laboratories (catalog mirrored at testcatalog.org), ATSDR (archived copy), ATSDR.

What can affect your result

  • Smoking and secondhand smoke, the biggest added source for most people
  • Age: cadmium builds up, so levels rise over a lifetime
  • Iron deficiency, which can increase how much cadmium the gut absorbs
  • Diet and workplace or neighborhood exposure
  • Kidney damage, which raises urine cadmium sharply
  • Recent contrast dye (gadolinium or iodine)
  • Whether the whole 24 hours of urine was collected
  • Gadolinium or iodine contrast dye can interfere with this kind of metal test. Mayo advises not collecting urine for 96 hours after a dose.
  • Use the clean plastic container your lab gives you. Mayo specifies no metal cap and no glued insert, because metal can contaminate the sample.
  • Missed urine makes the 24-hour total look lower than it is.
  • If your lab runs this together with arsenic, you may be asked to avoid seafood for 48 hours before and during the collection. The seafood advice is for the arsenic result.
  • Kidney damage can make urine cadmium rise sharply, so in that case the number no longer matches the total amount stored in the body.

A full 24-hour collection. Start by emptying your bladder and throwing that urine away, note the time, then collect all of your urine for the next 24 hours. Your lab will give you a container and exact steps. Changes slowly. At low to moderate exposure, urine cadmium reflects exposure built up over years rather than the last few days.

When to talk to a clinician

Talk with your clinician soon if your result is above your lab's range, especially if you smoke, work with cadmium, or have kidney or bone problems. Because cadmium builds up slowly, this is usually a planned conversation rather than an emergency. Get urgent care if you have breathed in fumes from heated or welded metal and have chest pain, fever or trouble breathing. These symptoms can start 4 to 10 hours later. In the US you can also call Poison Control at 1-800-222-1222.

Questions you could ask

  • How should I collect a 24-hour sample so the result is reliable?
  • How does my lab's range apply to my result?
  • Could smoking, my diet or my job explain this result?
  • Should we look at my kidney function alongside this test?
  • Would a result corrected for creatinine, or a repeat test, be useful?

Questions people ask

Why is urine used for cadmium instead of blood?

Cadmium leaves the body very slowly, so the amount in urine tracks what has built up over time. Blood cadmium mostly shows recent exposure.

Does smoking affect my cadmium result?

Yes. Tobacco smoke contains cadmium, so people who smoke and people who live with smokers usually have higher exposure than people who do not. For nonsmokers, food is the most common source.

Show the science and sources

Units

  • 1 µg/24 h = 1 µg/24 h
  • 1 µg/24 h = 8.896 nmol/24 h
  • 1 µg/24 h = 0.008896 µmol/24 h

Open the Cadmium (24-h urine) unit converter

For clinicians and researchers

Cadmium is absorbed from the gut (about 6% of an ingested dose, up to about 9% with iron deficiency) and from the lungs (10 to 50% of an inhaled dose), then bound to metallothionein and stored in the kidney and liver. The biologic half-life is 6 to 38 years in the kidney and 4 to 19 years in the liver. At low to moderate chronic exposure, urinary cadmium reflects integrated exposure and body burden. Once renal tubular binding sites are saturated and dysfunction develops, excretion rises sharply and urine reflects recent exposure instead. It does not rise meaningfully after a single acute exposure, so blood cadmium is used there. ATSDR names a 24-hour urinary cadmium, normalized to creatinine, as the best screening test for chronic exposure. NHANES data show an average of 0.08 µg/g creatinine in young nonexposed nonsmokers, rising to 0.26 with age. Renal dysfunction is considered unlikely below 10 µg/g creatinine, and Mayo cites an occupational Biological Exposure Index of 5 µg/g creatinine. Those thresholds are per gram of creatinine and cannot be applied to a per-24-hour amount. Mayo measures cadmium by ICP-MS/MS. Gadolinium and iodine contrast interfere with ICP-MS metal assays.

LOINC 5612-7 (primary), 32304-8. Specimen: urine-24h.

Sources

  1. Heavy Metals Screen, with Reflex, 24 Hour, Urine (Mayo test HMU24), 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 Toxicity: Laboratory Evaluation (Case Studies in Environmental Medicine), ATSDR (archived copy)
  4. Cadmium Toxicity: Biological Fate (Case Studies in Environmental Medicine), ATSDR (archived copy)
  5. Cadmium Toxicity: Clinical Assessment (Case Studies in Environmental Medicine), ATSDR (archived copy)
  6. ToxFAQs for Cadmium, ATSDR
  7. Cadmium (PubChem compound 23973), 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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