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Epic Code LAB1230730 Arsenic Speciation, 24 Hour, Urine

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Useful For

Diagnosing arsenic intoxication using 24-hour urine specimens

Specimen Type

Urine


Specimen Required


Patient Preparation:

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

2. 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 at least 96 hours.

Supplies: Urine Tubes, 10 mL (T068)

Collection Container/Tube: Clean, plastic urine collection container

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

Specimen Volume: 10 mL

Collection Instructions:

1. Collect urine for 24 hours.

2. Refrigerate urine specimen within 4 hours of completion of 24-hour collection

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

Additional Information: For multiple collections see Urine Preservatives-Collection and Transportation for 24-Hour Urine Specimens


Specimen Minimum Volume

3 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Urine Refrigerated (preferred) 28 days
  Frozen  28 days
  Ambient  72 hours

Urine Preservative Collection Options

Note: The addition of preservative or application of temperature controls must occur within 4 hours of completion of the collection.

Ambient

No

Refrigerate

Preferred

Frozen

OK

50% Acetic Acid

OK

Boric Acid

No

Diazolidinyl Urea

No

6M Hydrochloric Acid

OK

6M Nitric Acid

No

Sodium Carbonate

No

Thymol

No

Toluene

No

Reject Due To

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

Day(s) Performed

Monday through Friday

Reference Values

TOXIC ARSENIC

<35 mcg/L

Reference values apply to all ages.

 

Arsenic Speciation Interpretive Information:

The toxic arsenic concentration represents the sum of the inorganic and methylated arsenic species. The reference value for toxic arsenic is <35 mcg/L. This value is based on the American Conference of Governmental Industrial Hygienists (ACGIH) Biological Exposure Index (BEI), which does not include the non-toxic organic arsenic.

Clinical Information

Arsenic (As) exists in a number of different forms; some are toxic, while others are not. The toxic inorganic forms are arsenite (As[3+], As[III]) and arsenate (As[5+], As[V]), and their partially detoxified metabolites are monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA). As(III) is more toxic than As(V), and both are more toxic than MMA and DMA. The biologic half-life of inorganic arsenic is 4 to 6 hours, while the biologic half-life of the methylated metabolites is 20 to 30 hours. Target organs of As(III)-induced effects are the heart, gastrointestinal tract, skin and other epithelial tissues, kidney, and nervous system.

 

Inorganic arsenic is carcinogenic to humans. Symptoms of chronic poisoning, 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 occur.

 

Nontoxic, organic forms of arsenic are present in many foods. Arsenobetaine and arsenocholine are the 2 most common forms of organic arsenic found in food. The most common foods that contain significant concentrations of organic arsenic are shellfish and other predators in the seafood chain (cod, haddock, etc). Some meats, such as meats from chickens that have been fed seafood remnants, may also contain the organic forms of arsenic.

 

Following ingestion of arsenobetaine and arsenocholine, these compounds undergo rapid renal clearance to become concentrated in the urine. Organic arsenic is completely excreted within 1 to 2 days after ingestion, and there are no residual toxic metabolites. The biologic half-life of organic arsenic is 4 to 6 hours.

 

For reporting purposes, the concentrations of the inorganic forms (As[III] and As[V]) along with the methylated forms (MMA and DMA) will be summed and reported together as 'inorganic' arsenic. This is consistent with how the biological exposure index reference range is reported.

Cautions

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

Interpretation

The quantitative reference range for fractionated arsenic applies only to the inorganic forms. Concentrations of 20 mcg inorganic arsenic per liter or higher are considered toxic.

 

There is no limit to the normal range for the organic forms of arsenic since they are not considered to be toxic and are normally present after consumption of certain food types. For example, a typical finding in a urine specimen with total 24-hour excretion of arsenic of 350 mcg/24 hr would be that more than 95% is present as the organic species from a dietary source, and less than 5% is present as the inorganic species. This would be interpreted as indicating the elevated total arsenic was due to ingestion of the nontoxic form of arsenic, usually found in seafood.

 

A normal value for blood arsenic does not exclude a finding of elevated urine inorganic arsenic due to the very short half-life of blood arsenic.

Reporting Name

Arsenic Speciation, 24 Hr, U

Method Description

The metal analytes of interest are analyzed by inductively coupled plasma mass spectrometry.(Unpublished Mayo method)

CPT Code Information

82175

LOINC Code Information

Test ID Test Order Name Order LOINC Value
SPASU Arsenic Speciation, 24 Hr, U 96253-0

 

Result ID Test Result Name Result LOINC Value
609384 Inorganic Arsenic (Toxic) 41992-9
609385 Methylated Arsenic (Toxic) 96252-2
609386 Organic Arsenic (Non-Toxic) 43181-7
609406 Toxic Arsenic Concentration 96251-4
609387 Total Arsenic Concentration 21074-0

Report Available

3 to 5 days

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.

Clinical Reference

1. 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 Jan;19(1):59-68. doi: 10.1038/jes.2008.32

2. 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

3. 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