TEST CATALOG ORDERING & RESULTS SPECIMEN HANDLING CUSTOMER SERVICE EDUCATION & INSIGHTS
Test Catalog

Test ID: HMSOR    
Heavy Metal Occupational Exposure, with Reflex, Urine

Useful For Suggests clinical disorders or settings where the test may be helpful

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

Testing Algorithm Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

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

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

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 is a naturally occurring element that is usually found in the environment combined with other elements such as oxygen, chlorine, and sulfur. Arsenic combined with these elements is called inorganic arsenic. Arsenic combined with carbon and hydrogen is referred to as organic arsenic. The organic forms (eg, arsenobetaine and arsenocholine) are relatively nontoxic, while the inorganic forms are toxic. The toxic inorganic forms are arsenite (As3+/AsIII) and arsenate (As5+/AsV). Inorganic AsV is readily reduced to inorganic As(III) which is then primarily broken down to the less toxic methylated metabolites monomethylarsinic acid (MMA) and subsequently dimethylarsinic acid (DMA).

 

People are exposed to arsenic by eating food, drinking water, or breathing air. Of these, food is usually the largest source of arsenic. The predominant dietary source of arsenic is seafood, followed by rice/rice cereal, mushrooms, and poultry. While seafood contains the greatest amounts of arsenic, for fish and shellfish, this is mostly in an organic form of arsenic called arsenobetaine, which is much less harmful. Some seaweed may contain arsenic in the inorganic form, which is more toxic. In the United States, some areas also contain high natural levels of arsenic in rock, which can lead to elevated levels in the soil and drinking water. Occupational (eg, copper or lead smelting, wood treating, or pesticide application) exposure is another source where people may be introduced to elevated levels of arsenic. Lastly, hazardous waste sites may contain large quantities of arsenic and, if not disposed of properly, may get into the surrounding water, air, or soil.

 

A wide range of signs and symptoms may be seen in acute arsenic poisoning including headache, nausea, vomiting, diarrhea, abdominal pain, hypotension, fever, hemolysis, seizures, and mental status changes. Symptoms of chronic poisoning, also called arseniasis, are mostly insidious and nonspecific. The gastrointestinal tract, skin, and central nervous system are usually involved. Nausea, epigastric pain, colic abdominal pain, diarrhea, and paresthesias of the hands and feet can also occur.

 

Since arsenic is excreted predominantly by glomerular filtration, measurement of arsenic in urine is the most reliable means of detecting arsenic exposures within the last several days.

 

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(2+), it becomes toxic. Further bioconversion to an alkyl mercury, such as methyl Hg ([CH3Hg][+]), yields a species of mercury that is highly selective for lipid-rich tissue, such as the myelin sheath, and is very toxic.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

ARSENIC:

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

 

CADMIUM:

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

 

MERCURY:

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

 

LEAD:

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

Interpretation Provides information to assist in interpretation of the test results

Arsenic:

Mayo Clinic uses the American Conference of Governmental Industrial Hygienists (ACGIH) biological exposure index (BEI) as the reference value. The BEI is the sum of all the toxic species (inorganic arsenic plus methylated arsenic metabolites).

 

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 the toxic forms (eg, inorganic and methylated arsenic forms) or the relatively non-toxic organic forms (eg, arsenobetaine and arsenocholine).

 

The inorganic toxic forms of arsenic (eg, AsIII and AsV) are found in the urine shortly after ingestion, whereas the less toxic methylated forms (MMA and DMA) are the species that predominate longer than 24 hours after ingestion. In general, urinary AsIII and AsV 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 you have been exposed to above-average levels of arsenic. It cannot predict whether the arsenic levels in your body will affect your health.

 

Cadmium:

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.

 

Mercury:

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.

 

Lead:

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.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Consumption of seafood before collection of a urine specimen for arsenic testing is likely to result in a report of an elevated concentration of arsenic found in the urine, which can be clinically misleading.

 

Nitric acid cannot be added to either the collection or aliquot container. Nitrate interferes with the extraction procedure that would need to take place in the event of a positive arsenic result.

Clinical Reference Recommendations for in-depth reading of a clinical nature

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. doi: 10.1016/j.scitotenv.2009.11.046

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. doi: 10.1038/jes.2008.32

3. 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

4. Rifai N, Horwath AR, Wittwer CT, eds. Tietz Textbook of Clinical Chemistry and Molecular Diagnostics 6th ed. Elsevier; 2018

5. Keil DE, Berger-Ritchie J, McMillin GA: Testing for toxic elements: a focus on arsenic, cadmium, lead, and mercury. Lab Med, 2011 Dec:42(12):735–742. doi.org/10.1309/LMYKGU05BEPE7IAW

6. Navas-Acien A, Francesconi KA, Silbergeld EK, Guallar E. Seafood intake and urine concentrations of total arsenic, dimethylarsinate and arsenobetaine in the US population. Environ Res. 2011 Jan;111(1):110-118. doi: 10.1016/j.envres.2010.10.009

7. Tchounwou PB, Yedjou CG, Udensi UK, Pacurari M, Stevens JJ, Patlolla AK, Noubissi F, Kumar S. State of the science review of the health effects of inorganic arsenic: Perspectives for future research. Environ Toxicol. 2019 Feb;34(2):188-202. doi: 10.1002/tox.22673

8. 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

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

10. 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

Special Instructions Library of PDFs including pertinent information and forms related to the test