Arsenic with Reflex, 24 Hour, Urine
Use
Preferred screening test for detection of arsenic exposure using 24‑hour urine specimens. Measurement of urine total arsenic concentration is the most reliable means of detecting recent exposure, though if elevated, speciation is necessary to determine toxic inorganic versus benign organic forms of arsenic. Toxic inorganic As(III) and As(V) appear shortly after ingestion and return to normal within 20–30 hours, whereas methylated species (MMA, DMA) peak later and return to baseline over days. Seafood and environmental sources can elevate organic arsenic, potentially confounding interpretation.
Special Instructions
If gadolinium- or iodine-containing contrast media has been administered, specimen collection should be delayed for 96 hours. Patients should avoid seafood for 48 hours prior to collection. A clean plastic urine container with no metal cap or glued insert must be used; refrigerate within 4 hours of completion of the 24‑hour collection. The required specimen volume is 6 mL; collection duration (hours) and volume (mL) must be reported. Preservative options within 4 hours of collection include ambient (OK), refrigerated (Preferred), frozen (OK), 50% acetic acid (OK), 6M HCl or nitric acid (OK). Boric acid, diazolidinyl urea, sodium carbonate, thymol, and toluene are not acceptable.
Limitations
This test can determine elevated arsenic exposure but cannot predict health outcomes. The presence of organic arsenic (e.g., from seafood) can falsely elevate total arsenic. Specimen handling timing (collection timing, refrigeration) and contamination by contrast agents can interfere with results. Interpretation requires speciation when total arsenic ≥ 10 µg/L to distinguish toxic from benign forms. Reference ranges for individuals ≥18 years: <35 µg/24 h; for those <18 years: not established.
New York Approved
Methodology
Mass Spectrometry (ICP-MS/MS)
Biomarkers
LOINC Codes
- 5587-1
- 13362-9
- 3167-4
- 5587-1
- 21074-0
Result Turnaround Time
1-3 days
Related Documents
For more information, please review the documents below
Specimen
Urine
Volume
6 mL
Minimum Volume
Not provided
Container
Clean, plastic urine container with no metal cap or glued insert; submission in plastic 10‑mL tube or aliquot container with no metal cap or glued insert
Collection Instructions
Collect urine for 24 hours; refrigerate specimen within 4 hours of completion
Patient Preparation
Avoid seafood for 48 hours prior to collection; delay collection for 96 hours after gadolinium‑ or iodine‑containing contrast media
Causes for Rejection
Use of prohibited preservatives (boric acid, diazolidinyl urea, sodium carbonate, thymol, toluene) or metal-contaminated containers; inappropriate collection timing, failure to refrigerate within 4 hours
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | OK within 4 hours of collection |
| Refrigerated | Preferred |
| Frozen | OK |