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Test Code HMSOR Heavy Metal Occupational Exposure, with Reflex, Urine

Specimen Required

Patient Preparation:

-Patient should not eat seafood for a 48-hour period prior to start of collection.

-High concentrations of gadolinium and iodine are known to interfere with most metals 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 (T068) 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 Trace Metals Analysis Specimen Collection and Transport in Special Instructions for complete instructions.

Secondary ID


Useful For

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

Profile Information

Test ID Reporting Name Available Separately Always Performed
ARSO Arsenic Occupational Exposure Yes, (order ARSOR) Yes
CDOE Cadmium Occupational Exposure Yes, (order CDUO) Yes
HGOE Mercury Occupational Exposure Yes, (order HGUO) Yes
PBOE Lead Occupational Exposure Yes, (order PBUO) Yes
CDCR Creatinine Conc No Yes

Reflex Tests

Test ID Reporting Name Available Separately Always Performed
ASFRU Arsenic Fractionation, Random, U Yes No

Testing Algorithm

If arsenic concentration is greater than or equal to 35 mcg/L, then fractionation will be performed at an additional charge.

Method Name

ARSO, CDOE, HGOE, PBOE: Inductively Coupled Plasma-Mass Spectrometry (ICP-MS)

CDCR: Enzymatic Colorimetric Assay

Reporting Name

Heavy Metal Occupat Exp w/Reflex, U

Specimen Type


Specimen Minimum Volume

3 mL

Specimen Stability Information

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

Reject Due To

All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.

Clinical Information

Arsenic (As), lead (Pb), cadmium (Cd), and mercury (Hg) are well-known toxins and toxic exposures are characterized by increased urinary excretion of these metals.


Arsenic exists in a number of different forms; some are toxic while others are not. Toxic forms, which are typically encountered as a result of an industrial exposure, are the inorganic species As (+3) (As-III) and As (+5) (As-V) and the partially detoxified metabolites, monomethylarsine and dimethylarsine. The 2 most common nontoxic forms are arsenobetaine and arsenocholine. Arsenic toxicity affects a number of organ systems.


Lead toxicity primarily affects the gastrointestinal, neurologic, and hematopoietic systems.


Chronic exposure to cadmium causes accumulated renal damage.


Mercury is essentially nontoxic in its elemental form. However, once it is chemically modified to the ionized, inorganic species, Hg(++), it becomes toxic. Further bioconversion to an alkyl mercury, such as methyl Hg (CH[3]Hg[+]), yields a species of mercury that is highly selective for lipid-rich tissue, such as the myelin sheath, and is very toxic.

Reference Values


Biological Exposure Indices (BEI): <35 mcg/L at end of work week



Biological Exposure Indices (BEI): <5.0 mcg/g creatinine



Biological Exposure Index (BEI): <35 mcg/g creatinine



Biological Exposure Index (BEI): <150 mcg/g creatinine



Normally, humans consume 5 to 25 mcg of arsenic each day as part of their normal diet; therefore, normal urine arsenic output is below 35 mcg arsenic per gram creatinine (<35 mcg/g). When exposed to inorganic arsenic, the urine output may be more than 1,000 mcg/g and remain elevated for weeks. After a seafood meal (seafood contains a nontoxic, organic form of arsenic), on the other hand, the urine output of arsenic may be above 200 mcg/g, after which it will decline to below 35 mcg/g over a period of 1 to 2 days.

Exposure to inorganic arsenic, the toxic form of arsenic, causes prolonged excretion of arsenic in the urine for many days. Urine excretion rates above 1,000 mcg/g indicates significant exposure. The highest value observed at Mayo Clinic was 450,000 mcg/L in a patient with severe symptoms of gastrointestinal distress, shallow breathing with classic "garlic breath," intermittent seizure activity, cardiac arrhythmias, and later onset of peripheral neuropathy.



Cadmium excretion greater than 3.0 mcg/g creatinine indicates significant exposure to cadmium.


Results greater than 15 mcg/g creatinine are considered indicative of severe exposure.



Urinary mercury (Hg) is the most reliable way to assess exposure to inorganic Hg, but the correlation between the levels of excretion in the urine and clinical symptoms is poor.



Urinary excretion of less than 4 mcg/g creatinine is not associated with any significant lead exposure.


Urinary excretion of more than 4 mcg/g creatinine is usually associated with pallor, anemia, and other evidence of lead toxicity.

Clinical Reference

1. 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 Feb 1;408(5):1190-1194

2. Caldwell K, Jones R, Verdon C, et al: 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 Jan;19(1):59-68

3. 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 Jun;117(6):871-878

4. Kosnett MJ, Wedeen RP, Rotherberg SJ, et al: Recommendations for medical management of adult lead exposure. Environ Health Perspect 2007;115:463-471

5. 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;114:584-590

Day(s) and Time(s) Performed

Monday through Saturday; 7 p.m.

Analytic Time

1 day

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test Classification

See Individual Test IDs

CPT Code Information






LOINC Code Information

Test ID Test Order Name Order LOINC Value
HMSOR Heavy Metal Occupat Exp w/Reflex, U In Process


Result ID Test Result Name Result LOINC Value
CDCR Creatinine Conc 2161-8
48551 Arsenic Occupational Exposure 13463-5
48554 Cadmium Occupational Exposure 13471-8
48556 Mercury Occupational Exposure 13465-0
48558 Lead Occupational Exposure 13466-8
48552 Arsenic Concentration w/Reflex 5586-3