Update Type: Test Code Change
Test Updated: 03/16/2022
Test Overview
Test Methodology
Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)
Test Usage
Monitor therapeutic drug level
Reference Range *
Therapeutic: 0.5 - 2.0 mcg/mL; Toxic: greater than 2 mcg/mL.
* Reference ranges may change over time. Please refer to the original patient report when evaluating results.
Test Details
Days Set Up
Monday - Saturday
Analytic Time
2 - 6 days
Soft Order Code
MEX
Laboratory
Sendout
Reference Laboratory
Mayo MEX (9245)
Section
Special Testing
Specimen Requirements
Collection Instructions
Collect a trough specimen in a red top tube after patient has been receiving Mexiletine for at least 3 days; do not use SST tube. Centrifuge within 2 hours of collection, aliquot serum into a plastic vial and refrigerate.
Normal Volume
1.5 mL serum
Minimum Volume
0.5 mL serum
Rejection Criteria
SST tube not acceptable.
Additional Information
Test sent to Mayo Clinic Laboratories.
Billing
CPT Code
80299
Fee Code
20039
LOINC
3819-0