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Test Code Billings Clinic: 8793 Mayo: MEX Mexiletine, Serum

Reporting Name

Mexiletine, S

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Useful For

Assessing achievement of optimal therapeutic mexiletine concentrations

 

Assessing potential mexiletine toxicity

Method Name

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


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 Type

Serum Red

Specimen Minimum Volume

0.5 mL

Specimen Stability Information

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

Reject Due To

Gross hemolysis OK
Gross lipemia OK
Gross icterus OK

Reference Values

Trough Value

0.5-2.0 mcg/mL: Therapeutic concentration

>2.0 mcg/mL: Toxic concentration

Interpretation

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

Day(s) Performed

Monday through Friday

Report Available

2 to 5 days

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

Forms

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