Cathartic Laxatives Profile, Stool
Use
This test evaluates concentrations of magnesium and phosphorus in stool, assisting in detection of surreptitious abuse of magnesium-containing cathartic laxatives. Elevated magnesium levels above normal stool water levels (0.7–1.2 mg/mL) are indicative of laxative misuse, with reference–derived nomograms by NMS Labs estimating normative stool magnesium (≈ 0.5–10 mg/g) and phosphorus (≈ 1.4–22 mg/g) elimination values.
Special Instructions
Specimens must be collected in acid‑washed or trace metal‑free plastic containers (MCL supply T656) to avoid contamination. One stool specimen (10 g solid or 10 mL liquid) per order; specimens cannot be shared between orders and should be refrigerated at collection and transport. Unexpected elevated results should be verified by retesting using a trace metal‑free container.
Limitations
This is a laboratory‑developed test not cleared or approved by the U.S. Food and Drug Administration. Environmental contamination during specimen collection can artifactually elevate elemental concentrations. Reporting limits are determined per analysis and may vary. Interpretation must consider possible contamination and analytic variability.
Methodology
Mass Spectrometry (ICP-OES)
Biomarkers
LOINC Codes
- 10880-3
- 10884-5
Result Turnaround Time
10-14 days
Related Documents
For more information, please review the documents below
Specimen
Stool
Volume
10 g
Minimum Volume
10 mL stool liquid or 10 g stool solid
Container
Acid‑washed or trace metal‑free plastic container, MCL supply T656
Collection Instructions
Collect 10 g of stool with no preservative. Send specimen in an acid‑washed or trace metal‑free plastic container, MCL supply T656. Send specimen refrigerated.
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 30 days |
| Refrigerated | 30 days |
| Frozen | 30 days |