Arsenic/Creatinine Ratio, Urine
Use
Preferred screening test for detection of arsenic exposure using random urine specimens. If total arsenic concentration is elevated (≥10 µg/L), a reflex speciation test may be performed to determine if the exposure is to toxic inorganic and methylated forms versus relatively nontoxic organic forms. It assists in identifying recent arsenic exposure through urinary excretion and helps guide clinical interpretation rather than predict long-term health outcomes. ([mayocliniclabs.com](https://www.mayocliniclabs.com/test-catalog/overview/608905?utm_source=openai))
Special Instructions
Only orderable as part of a profile (includes ASCU and CRETR). A testing algorithm triggers reflex to SPAS (Arsenic Speciation) if total arsenic reaches or exceeds 10 µg/L, at additional charge. Available for New York State clients. ([mayocliniclabs.com](https://www.mayocliniclabs.com/test-catalog/overview/608905?utm_source=openai))
Limitations
Elevated total arsenic levels may be influenced by recent seafood consumption, which contains organic arsenic forms that are not harmful but may confound interpretation. High concentrations of gadolinium or iodine contrast agents can interfere with metal testing and specimens should not be collected within 96 hours of administration. Interpreting exposures is limited to recent days—this test does not assess long-term burden or health impact directly. ([mayocliniclabs.com](https://www.mayocliniclabs.com/test-catalog/overview/608900?utm_source=openai))
New York Approved
Methodology
Mass Spectrometry (LC-MS/MS)
Biomarkers
LOINC Codes
- 13463-5
- 13463-5
- 5586-3
Result Turnaround Time
2-4 days
Related Documents
For more information, please review the documents below
Specimen
Urine
Volume
6 mL
Minimum Volume
3 mL
Container
Clean, plastic urine container with no metal cap or glued insert; submission in plastic 10-mL urine tube or clean plastic aliquot container with no metal cap or glued insert
Collection Instructions
Collect a random urine specimen; patient should not eat seafood for 48 hours prior; avoid specimen collection for 96 hours after gadolinium‑ or iodine‑based contrast administration
Patient Preparation
No seafood 48 hours prior; avoid gadolinium or iodine contrast for 96 hours
Causes for Rejection
All specimens evaluated for suitability; high contrast administration or recent seafood may confound results
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 72 hours |
| Refrigerated | 28 days |
| Frozen | 28 days |