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HelpTest Code KEP Levetiracetam, Serum
Additional Codes
| Mayo Test ID |
|---|
| LEVE |
Reporting Name
Levetiracetam, SUseful For
Monitoring serum concentration of levetiracetam, particularly in patients with kidney disease
Assessing compliance with levetiracetam therapy
Assessing potential toxicity of levetiracetam
Method Name
Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
SerumSpecimen Required
Supplies: Sarstedt Aliquot Tube 5 mL (T914)
Collection Container/Tube:
Preferred: Red top
Acceptable: Serum gel
Submission Container/Tube: Plastic vial
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. Within 2 hours of collection, centrifuge, and aliquot serum into a plastic vial
Specimen Minimum Volume
0.5 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum | Refrigerated (preferred) | 28 days | |
| Ambient | 28 days | ||
| Frozen | 28 days |
Reject Due To
| Gross hemolysis | OK |
| Gross lipemia | OK |
| Gross icterus | OK |
Reference Values
10.0-40.0 mcg/mL
Day(s) Performed
Monday through Sunday
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. Kidney dysfunction may warrant therapeutic monitoring and/or dose adjustment.
Given the lack of drug interactions and favorable 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 10.0 to 40.0 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 collected at trough (ie, immediately before the next dose).
Cautions
This test cannot be performed on whole blood.
Method Description
The serum sample is diluted in acetonitrile containing internal standard. The protein precipitate is centrifuged, and a portion of the supernatant is diluted with mobile phase for detection by a tandem mass spectrometer.(Unpublished Mayo method)