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Test Code MEX Mexiletine, Serum

Reporting Name

Mexiletine, S

Useful For

Assessing achievement of optimal therapeutic mexiletine concentrations

 

Assessing potential mexiletine toxicity

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Specimen Type

Serum Red


Specimen Required


Patient Preparation: Specimens should only be collected after patient has been receiving mexiletine for at least 3 days. Trough concentrations should be collected just before administration of the next dose.

Supplies: Sarstedt Aliquot Tube, 5 mL (T914)

Collection Container/Tube: Red top (serum gel/SST are not acceptable)

Submission Container/Tube: Plastic vial

Specimen Volume: 1.5 mL

Collection Instructions:

1. Draw blood immediately before next scheduled dose.

2. Centrifuge and aliquot serum into a plastic vial within 2 hours of collection.


Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time
Serum Red Refrigerated (preferred) 28 days
  Ambient  28 days
  Frozen  28 days

Reference Values

Trough Value

0.5-2.0 mcg/mL: Therapeutic concentration

>2.0 mcg/mL: Toxic concentration

Day(s) Performed

Monday through Friday

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information

80299

LOINC Code Information

Test ID Test Order Name Order LOINC Value
MEX Mexiletine, S 40779-1

 

Result ID Test Result Name Result LOINC Value
9245 Mexiletine, S 40779-1

Interpretation

Optimal response to mexiletine occurs when the serum concentration is within the range of 0.5 to 2.0 mcg/mL (trough value).

Clinical Reference

1. Milone MC, Shaw LM. Therapeutic drugs and their management. In: Rifai N, Chiu RWK, Young I, Burnham CAD, Wittwer CT, eds. Tietz Textbook of Laboratory Medicine. 7th ed. Elsevier; 2023:420-453

2. Josephson ME, Buxton AE, Marchlinski FE. The tachyarrhythmias: tachycardias. In: Wilson JD, Braunwald E, Isselbacher KJ, et al, eds. Harrison's Principles of Internal Medicine. 12th ed. McGraw-Hill Book Company; 1991:915

3. Valdes R Jr, Jortani SA, Gheorghiade M. Standards of laboratory practice: cardiac drug monitoring. National Academy of Clinical Biochemistry. Clin Chem. 1998;44(5):1096-1099

4. Joseph SP, Holt DW: Electrophysiological properties of mexiletine assessed with respect to plasma concentrations. Eur J Cardiol. 1980;11(2):115-121

Report Available

2 to 5 days

Method Name

Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)

Forms

If not ordering electronically, complete, print, and send a Therapeutics Test Request (T831) with the specimen.