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Test Code LEVE Levetiracetam, Serum

Reporting Name

Levetiracetam, S

Useful For

Monitoring serum concentration of levetiracetam, particularly in patients with renal disease

 

Assessing compliance

 

Assessing potential toxicity

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Specimen Type

Serum


Specimen Required


Container/Tube:

Preferred: Red top

Acceptable: Serum gel

Specimen Volume: 1 mL

Collection Instructions:

1. Draw blood immediately before next scheduled dose.

2. For sustained-release formulations ONLY, draw blood a minimum of 12 hours after last dose.

3. Spin down within 2 hours of draw.


Specimen Minimum Volume

0.5 mL

Specimen Stability Information

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

Reference Values

12.0-46.0 mcg/mL

Day(s) and Time(s) Performed

Monday through Friday; Continuous until 2 p.m.

Saturday; Continuous until 1 p.m.

Sunday; 11 a.m.

Test Classification

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

CPT Code Information

80177

LOINC Code Information

Test ID Test Order Name Order LOINC Value
LEVE Levetiracetam, S 30471-7

 

Result ID Test Result Name Result LOINC Value
83140 Levetiracetam, S 30471-7

Clinical Information

Levetiracetam is approved for treatment of partial, myoclonic, and tonic-clonic seizures, and is used off-label for manic states and migraine prophylaxis. Levetiracetam has very favorable pharmacokinetics with good bioavailability and rapid achievement of steady state. Its hepatic metabolism is minimal and nonoxidative, making it safe for use with hepatic enzyme inducers or inhibitors. The major metabolite is a carboxylic acid derivate, which is inactive and accounts for roughly one quarter of the administered dose. Levetiracetam is excreted renally, with a mean half-life of 7 hours in adults and slightly less than that in children. Renal dysfunction may warrant therapeutic monitoring and/or dose adjustment.

 

Given the lack of drug interactions and favorably pharmacokinetics, the primary uses for therapeutic drug monitoring of levetiracetam are compliance assurance and management of physiological changes such as puberty, pregnancy, and aging. Toxicities associated with levetiracetam use include decreased hematocrit and red blood cell count, decreased neutrophil count, somnolence, asthenia, and dizziness. These toxicities may be associated with blood concentrations in the therapeutic range.

Interpretation

Most individuals display optimal response to levetiracetam with serum levels 12 to 46 mcg/mL. Some individuals may respond well outside of this range, or may display toxicity within the therapeutic range; thus, interpretation should include clinical evaluation. Toxic levels have not been well established. Therapeutic ranges are based on specimen drawn at trough (ie, immediately before the next dose).

Cautions

This test cannot be performed on whole blood.

Clinical Reference

1. Patsalos PN, Berry DJ, Bourgeois BF, et al: Antiepileptic drugs-best practice guidelines for therapeutic drug monitoring: a position paper by the subcommission on therapeutic drug monitoring. ILAE Commission on Therapeutic Strategies. Epilepsia 2008 Jul;49(7):1239-1276

2. Johannessen SI, Tomson T: Pharmacokinetic variability of newer antiepileptic drugs: when is monitoring needed? Clin Pharmacokinet 2006;45(11):1061-1075

Method Description

Samples are diluted and extracted online extraction by high-turbulence liquid chromatography, with detection by tandem mass spectrometry.(Unpublished Mayo method)

Analytic Time

Same day/1 day

Specimen Retention Time

14 days

Reject Due To

Hemolysis

Mild OK; Gross OK

Lipemia

Mild OK; Gross OK

Icterus

Mild OK; Gross OK

Other

NA

NY State Approved

Yes

Method Name

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

Forms

If not ordering electronically, complete, print, and send 1 of the following forms with the specimen:

-Neurology Specialty Testing Client Test Request (T732) (http://www.mayomedicallaboratories.com/it-mmfiles/neurology-request-form.pdf)

-General Request (T239) (http://www.mayomedicallaboratories.com/it-mmfiles/general-request-form.pdf)