Test Overview

Test Methodology

Inductively Coupled Plasma Optical Emission Spectrometry (ICP/OES)

Test Usage

Compliance or Abuse Monitoring of Laxatives

Reference Range*

MAGNESIUM: Magnesium concentrations in stool water above the normal levels of 0.7 - 1.2 mg/mL have been indicative of surreptitious abuse of magnesium containing laxatives. NMS Labs Calculated Normal: approximately 0.5 - 10 mg/g. PHOSPHORUS: Phosphorus concentration in stool water averaged 1.8 +/- 0.3 mg/mL (ranged from 0.3 - 4.2 mg/mL) following administration of 105 mmol of sodium phosphate. NMS Labs calculated normal: approximately 1.4 - 22 mg/g.

* Reference ranges may change over time. Please refer to the original patient report when evaluating results.

Test Details

Days Test Performed

Varies, Monday, Tuesday, Wednesday, Friday

Analytic Time

7 - 12 days

Soft Order Code




Phosphorus, Stool
Magnesium, Stool

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Laboratory Reference

Mayo FCLPS (91193) (NMS 1033ST)

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Specimen Requirements

Offsite Collection Instructions

Collect random stool specimen and refrigerate.

Normal Volume

10 grams (solid) or 10 mL (fluid) stool

Additional Information

Test includes Magnesium [FAAS] and Phosphorus [ICP/MS]. Test sent to Mayo Medical Laboratories; performed by NMS Labs.

Billing Information

Fee Codes

CPT Code

80103 x2, 83735, 84100

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