Detecting chromium exposure
|Test Id||Reporting Name||Available Separately||Always Performed|
|CRCRR||Chromium/Creat Ratio, U||No||Yes|
|CRETR||Creatinine, Random, U||No||Yes|
CRETR: Enzymatic Colorimetric Assay
High concentrations of gadolinium and iodine are known to interfere with most metal tests. If either gadolinium- or iodine-containing contrast media has been administered, a specimen should not be collected for 96 hours.
Supplies: Urine Tubes, 10 mL
Collection Container/Tube: Clean, plastic urine container with no metal cap or glued insert
Submission Container/Tube: Plastic vial or clean, plastic aliquot container with no metal cap or glued insert
Specimen Volume: 3 mL
1. Collect a random urine specimen.
2. See Trace Metals Analysis Specimen Collection and Transport for complete instructions.
|Specimen Type||Temperature||Time||Special Container|
|Urine||Refrigerated (preferred)||28 days|
Detecting chromium exposure
Chromium (Cr) has an atomic mass of 51.996, atomic number 24, and valences ranging from 2to 6(+). Hexavalent chromium, Cr(6+), and trivalent chromium, Cr(3+), are the 2 most prevalent forms. Cr(3+) is the only oxidation state present under normal physiologic conditions. Cr(6+) is widely used in industry to make chromium alloys including stainless steel pigments and electroplated coatings. Cr(6+), a known carcinogen, is rapidly metabolized to Cr(3+). Cr(3+) is the only form present in human urine.
0-17 years: Not established
>17 years: <0.8 mcg/g Creatinine
Chromium is principally excreted in the urine. Results greater than the reference range indicate either recent exposure to chromium or specimen contamination during collection.
The National Institute for Occupational Safety and Health document on occupational exposure reviews the data supporting use of urine to assess chromium exposure. The biological exposure index (BEI) for total chromium in urine measured at the end of the shift at the end of the workweek is 25 mcg/L. The BEI for the increase in total chromium during a shift is 10 mcg/L. A test for this specific purpose (CRUO / Chromium Occupational Exposure, Random, Urine) is available.
Normal specimens have extremely low levels of creatinine; elevated results could easily be a result of external contamination. Precautions must be taken to ensure the specimen is not contaminated. Metal-free urine collection procedures must be followed. Refrigeration is preferred over chemical methods of preservation.
Specimen collection procedures for chromium require special specimen collection tubes, rigorous attention to ultraclean specimen collection and handling procedures, and analysis in an ultraclean facility. Unless all of these precautions are taken, elevated urine chromium results may be an incidental and misleading finding.
1. U.S. Department of Health and Human Services, Agency for Toxic Substances and Disease Registry. Toxicology profile for chromium. HHS; September 2012. Accessed 11/06/2020. Available at www.atsdr.cdc.gov/ToxProfiles/tp7.pdf
2. Roberts NB, Taylor A, Sodi R: Vitamins and trace elements. Rifai N, Horwath AR, Wittwer CT, eds: Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. 6th ed. Elsevier; 2018:chap 37
3. Centers for Disease Control and Prevention: National Institute for Occupational Safety and Health (NIOSH): Criteria for a recommended standard occupational exposure to hexavalent chromium. CDC; September 2013. Accessed 11/06/2020. Available at www.cdc.gov/niosh/docs/2013-128/pdfs/2013_128.pdf
4. Gianello G, Masci O, Carelli G, Vinci F, Castellino N: Occupational exposure to chromium-an assessment of environmental pollution levels and biological monitoring of exposed workers. Ind Health. 1998 Jan;36(1):74-77. doi: 10.2486/indhealth.36.74.
5. Eliaz N. Corrosion of metallic biomaterials: A review. Materials (Basel). 2019 Jan 28;12(3):407. doi: 10.3390/ma12030407
6. US Food and Drug Administration: Information about Soft Tissue Imaging and Metal Ion Testing. FDA; Updated March 15, 2019. Accessed March 2, 2021. Available at: www.fda.gov/MedicalDevices/ProductsandMedicalProcedures/ImplantsandProsthetics/MetalonMetalHipImplants/ucm331971.htm
Chromium in urine is analyzed by inductively coupled plasma-mass spectrometry in dynamic reaction cell mode using rhodium as an internal standard and a salt matrix calibration.(Unpublished Mayo method)
Creatinine is measured using an enzymatic method based on the determination of sarcosine from creatinine with the aid of creatininase, creatinase, and sarcosine oxidase. The liberated hydrogen peroxide is measured via a modified Trinder reaction using a colorimetric indicator.(Package insert: Creatinine plus ver 2. Roche Diagnostics; V15.0 03/2019)
Tuesday, Wednesday, Friday
This test was developed, and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.
|Test Id||Test Order Name||Order LOINC Value|
|CRCRU||Chromium/Creat Ratio, Random, U||13464-3|
|Result Id||Test Result Name||
Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
|CRETR||Creatinine, Random, U||2161-8|
|607759||Chromium/Creat Ratio, U||13464-3|