Arsenic w/Rflx Fractions, URN (Sendout)

Useful For: Screening test for detection of arsenic exposure using 24-hour urine specimens.

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

Note: If a random urine specimen is submitted, the Arsenic/Creatinine Ratio with Reflex, Random Urine test will be performed and results will be reported under Reference Laboratory Test 1 (SEND1).

Interpretation:

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 forms) or the relatively nontoxic organic forms (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 (monomethylarsinic acid: MMA 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.

After a seafood meal (seafood generally contains the nontoxic, organic form of arsenic (eg, arsenobetaine), the urine output of arsenic may increase to over 300 mcg/24 hour, after which it will decline.

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

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.

Collection:

• 24-Hr Collection:
  • Collect urine for 24 hours in a preservative-free amber polyethylene 24-hr urine collection container (with no metal caps or glued inserts).
  • Refer to Mayo Urine Preservatives-Collection and Transportation for 24-Hour Urine Specimens for additional information on acceptable collection conditions.
  • Refrigerate urine within 4 hours of completion of collection.
• Random Urine: Collect random urine in a sterile screw-cap container (with no metal cap or glued insert).

Outside Laboratories:

• 24-Hour Collection:
  • Mix specimen well. Measure and record total volume. Note the collection interval and total volume on the requisition.
  • Aliquot urine into a Mayo metal-free screw-capped vial (T173)* and refrigerate.
• Random Urine: Aliquot urine into a Mayo metal-free screw-capped vial (T173)* and refrigerate.

*Note: Mayo T173 is recommended, but not required.

Stability: Refrigerated (preferred): 28 days; Frozen: 28 days; Ambient: 72 hours.

SPS: Specimen must be refrigerated within 4 hours of completion of 24-hour collection.

• 24-Hour Urine: Mix specimen well. Measure and record total volume. Aliquot urine into a Mayo metal-free screw-capped vial (T173)* and refrigerate.
• Random Urine: Aliquot urine into a Mayo metal-free screw-capped vial (T173)* and refrigerate.

*Note: Mayo T173 is recommended, but not required.

Sendouts:

• 24-Hour Urine: Order Mayo Test: ASU24.
• Random Urine: Order Mayo Test: ASUCR (Arsenic/Creatinine Ratio w/ Reflex, Rand Urine).
  • Batch RUARSX on the interface. Add test ASUCR and delete test ASU24 in MayoAccess prior to closing the batch.
• Interfaced: Yes.

Stability: Refrigerated (preferred): 28 days; Frozen: 28 days; Ambient: 72 hours.