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Test Code HMUCR Heavy Metal/Creatinine Ratio, with Reflex, Random, Urine


Specimen Required


1. For the 48-hour period prior to start of collection, patient should not eat seafood.

2. High concentrations of gadolinium and iodine are known to potentially interfere with most inductively coupled plasma mass spectrometry-based 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 (T068)

Collection Container/Tube: Clean, plastic urine container with no metal cap or glued insert

Submission Container/Tube: Plastic, 10-mL urine tube or clean, plastic aliquot container with no metal cap or glued insert

Specimen Volume: 6 mL

Collection Instructions:

1. Collect a random urine specimen.

2. See Metals Analysis Specimen Collection and Transport for complete instructions.


Useful For

Preferred screening test for detection of arsenic, cadmium, mercury, and lead in random urine specimens

Profile Information

Test ID Reporting Name Available Separately Always Performed
ASCU Arsenic/Creatinine Ratio, U Yes, (order ASUCR) Yes
CDCU Cadmium/Creatinine Ratio, U Yes, (order CDUCR) Yes
HGCU Mercury/Creatinine Ratio, U Yes, (order HGUCR) Yes
PBCU Lead/Creatinine Ratio, U Yes, (order PBUCR) Yes
CRETR Creatinine, Random, U No Yes

Reflex Tests

Test ID Reporting Name Available Separately Always Performed
SPAS Arsenic Speciation, Random, U Yes No

Testing Algorithm

If the total arsenic concentration is 10 mcg/L or greater, then speciation will be performed at an additional charge.

 

For more information see Porphyria (Acute) Testing Algorithm

Method Name

ASCU, CDCU, HGCU, PBCU: Triple-Quadrupole Inductively Coupled Plasma Mass Spectrometry (ICP-MS/MS)

CRETR: Enzymatic Colorimetric Assay

Reporting Name

Heavy Metal/Creat Ratio,w/Reflex,U

Specimen Type

Urine

Specimen Minimum Volume

3 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Urine Refrigerated (preferred) 7 days
  Frozen  7 days

Reference Values

ARSENIC/CREATININE:

0-17 years: Not established

≥18 years: <24 mcg/g creatinine

 

CADMIUM/CREATININE:

0-17 years: Not established

≥18 years: <0.6 mcg/g creatinine

 

MERCURY/CREATININE:

0-17 years: Not established

≥18 years: <2 mcg/g creatinine

 

LEAD/CREATININE:

0-17 years: Not established

≥18 years: <2 mcg/g creatinine

 

CREATININE:

≥18 years: 16-326 mg/dL

Reference values have not been established for patients who are younger than 18 years.

Interpretation

Arsenic:

Physiologically, arsenic exists in a number of toxic and nontoxic forms. The total arsenic concentration reflects all the arsenic present in the sample regardless of species (eg, inorganic vs. methylated vs. organic arsenic). The measurement of urinary total arsenic levels is generally accepted as the most reliable indicator of recent arsenic exposure. However, if the total urine arsenic concentration is elevated, arsenic speciation must be performed to identify if it is a toxic form (eg, inorganic and methylated forms) or a relatively nontoxic organic form (eg, arsenobetaine and arsenocholine).

 

The inorganic toxic forms of arsenic (eg, As[III] and As[V]) are found in the urine shortly after ingestion, whereas the less toxic methylated forms, monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA), are the species that predominate longer than 24 hours after ingestion. In general, urinary As(III) and As(V) concentrations peak in the urine at approximately 10 hours and return to normal 20 to 30 hours after ingestion. Urinary MMA and DMA concentrations normally peak at approximately 40 to 60 hours and return to baseline 6 to 20 days after ingestion.

 

This test can determine if a patient has been exposed to above-average levels of arsenic. It cannot predict whether the arsenic levels in their body will affect their health.

 

Cadmium:

Urine cadmium levels primarily reflect total body burden of cadmium. Cadmium excretion above 3.0 mcg/g creatinine indicates significant exposure to cadmium.

 

For occupational testing, OSHA cadmium standard is below 3.0 mcg/g creatinine, and the biological exposure index is 5 mcg/g creatinine.

 

Mercury:

The correlation between the levels of mercury (Hg) excretion in the urine and the clinical symptoms is considered poor.

 

Previous thought indicated urine as a more appropriate marker of inorganic mercury because organic mercury represented only a small fraction of urinary mercury. Based on possible demethylation of methylmercury within the body, urine may represent a mixture of dietary methylmercury and inorganic mercury. Seafood consumption can contribute to urinary mercury levels (up to 30%),(1) consistent with the suggestion that due to demethylation processes in the human body, a certain proportion of urinary mercury can originate from dietary consumption of fish/seafood.(2)

 

Lead:

Measurements of urinary lead levels have been used to assess lead exposure. However, like lead blood, urinary lead excretion mainly reflects recent exposure and thus shares many of the same limitations for assessing lead body burden or long-term exposure.(3,4)

 

Urinary lead concentration increases exponentially with blood lead and can exhibit relatively high intra-individual variability, even at similar blood lead concentrations.(5,6)

Clinical Reference

1. Tratnik JS, Falnoga I, Mazej D, et al. Results of the first national human biomonitoring in Slovenia: Trace elements in men and lactating women, predictors of exposure and reference values. Int J Hyg Environ Health. 2019;222(3):563-582. doi:10.1016/j.ijheh.2019.02.008

2. Sherman LS, Blum JD, Franzblau A, Basu N. New insights into biomarkers of human mercury exposure using naturally occurring mercury stable isotopes. Envrn Sci Technol. 2013;47(7):3403-3409. doi:10.1021/es305250z

3. Sakai T. Biomarkers of lead exposure. Ind Health. 2000;38(2):127-142. doi:10.2486/indhealth.38.127

4. Skerfving S. Biological monitoring of exposure to inorganic lead. In: Clarkson TW, Friberg L, Nordberg GF, Sager PR, eds. Biological Monitoring of Toxic Metals. Rochester Series on Environmental Toxicity. Springer; 1988:169-197

5. Gulson BL, Jameson CW, Mahaffey KR, et al. Relationships of lead in breast milk to lead in blood, urine, and diet of the infant and mother. Environ Health Perspect. 1998;106(10):667-667. doi:10.1289/ehp.98106667

6. Skerfving S, Ahlgren L, Christoffersson JO. Metabolism of inorganic lead in man. Nutr Res. 1985;Suppl 1:601-607

7. Fillol CC, Dor F, Labat L, et al. Urinary arsenic concentrations and speciation in residents living in an area with naturally contaminated soils. Sci Total Environ. 2010;408(5):1190-1194. doi:10.1016/j.scitotenv.2009.11.046

8. Caldwell KL, Jones RL, Verdon CP, Jarrett JM, Caudill SP, Osterloh JD. Levels of urinary total and speciated arsenic in the US population: National Health and Nutrition Examination Survey 2003-2004. J Expo Sci Environ Epidemiol. 2009;19(1):59-68. doi:10.1038/jes.2008.32

9. Lee R, Middleton D, Caldwell K, et al. A review of events that expose children to elemental mercury in the United States. Environ Health Perspect. 2009;117(6):871-878. doi:10.1289/ehp.0800337

10. Kosnett MJ, Wedeen RP, Rotherberg SJ, et al. Recommendations for medical management of adult lead exposure. Environ Health Perspect. 2007;115(3):463-471. doi:10.1289/ehp.9784

11. de Burbane C, Buchet JP, Leroyer A, et al. Renal and neurologic effects of cadmium, lead, mercury, and arsenic in children: evidence of early effects and multiple interactions at environmental exposure levels. Environ Health Perspect. 2006;114(4):584-590. doi:10.1289/ehp.8202

12. Agency for Toxic Substances and Disease Registry. Toxicological profile for arsenic. US Department of Health and Human Services; 2007. Available at www.atsdr.cdc.gov/ToxProfiles/tp2.pdf

13. Bernhoft RA. Mercury toxicity and treatment: a review of the literature. J Environ Public Health. 2012;2012:460508. doi:10.1155/2012/460508

14. Strathmann FG, Blum LM. Toxic elements. In: Rifai N, Chiu RWK, Young I, Burnham CD, Wittwer CT, eds. Tietz Textbook of Laboratory Medicine. 7th ed. Elsevier; 2023:chap 44

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information

82175

82300

83825

83655

82570

LOINC Code Information

Test ID Test Order Name Order LOINC Value
HMUCR Heavy Metal/Creat Ratio,w/Reflex,U 29589-9

 

Result ID Test Result Name Result LOINC Value
608902 Cadmium/Creatinine Ratio, U 13471-8
608903 Mercury/Creatinine Ratio, U 13465-0
608904 Lead/Creatinine Ratio, U 13466-8
CRETR Creatinine, Random, U 2161-8
608900 Arsenic/Creatinine Ratio, U 13463-5
608901 Total Arsenic Concentration 5586-3

Day(s) Performed

Monday through Friday

Report Available

2 to 4 days