Levetiracetam, Serum or Plasma

CPT: 80177
Print Share

Test Details


  • Keppra®


Liquid chromatography/tandem mass spectrometry (LC/MS-MS)

Reference Interval

10−40 μg/mL

Additional Information

Levetiracetam (LTA), a piracetam analogue, is an antiepileptic drug (AED) structurally unrelated to other AEDs. The exact mechanism by which LTA acts has not been determined at this time; however, binding sites for the drug have been identified in synaptic plasma membranes of CNS neurons. Secondary alteration in GABA-related enzymes may result from binding to neurons in specific regions of the CNS.1 While approximately one-fourth of LTA is converted by enzymatic hydrolysis to a carboxylic acid metabolite, the drug has no effect on UDP glucuronyltransferase, epoxide hydrolase, or enzymes in the CYP system,1,2 resulting in minimal interactions with other AEDs in a polypharmacy regimen. LTA has minimal protein binding (<10%), an elimination half-life of six to eight hours in healthy adults, six hours in children, and 10-11 hours in the elderly. In healthy adults, approximately 95% of LTA and metabolites are excreted in the urine. Renal impairment can, therefore, decrease clearance from 35% to 60%.3,4

A single 1000 mg dose or 1000 mg twice daily doses produced peak levels of 31 μg/mL and 43 μg/mL, respectively.3 Neuropsychiatric adverse events of aggression, anger, and irritability, as well as adverse reactions of leukopenia, neutropenia, pancytopenia, and thrombocytopenia have been reported.5

Specimen Requirements


Serum or plasma


1 mL

Minimum Volume

0.2 mL


Red-top tube, lavender-top (EDTA) tube, or green-top (heparin) tube. Do not use a gel-barrier tube. The use of gel-barrier tubes is not recommended due to slow absorption of the drug by the gel. Depending on the specimen volume and storage time, the decrease in drug level due to absorption may be clinically significant.


Transfer separated serum or plasma to a plastic transport tube.

Storage Instructions

Maintain specimen at room temperature.

Stability Requirements



Room temperature

14 days


14 days


105 days

Freeze/thaw cycles

Stable x3

Causes for Rejection

Gel-barrier tube

Clinical Information


1. Willmore LJ. Clinical pharmacology of new antiepileptic drugs. Neurology. 2000; 55(11 Suppl 3):S17-24. 11147564
2. Wheless JW. Using the new antiepilepsy drugs in children. J Child Neurol. 2002 Jan; 17(Suppl 1):S58-64. 11918465
3. Patsalos PN. Pharmacokinetic profile of levetiracetam: Toward ideal characteristics. Pharm Ther. 2000 Feb; 85(2):77-85. 10722121
4. Radtke RA. Pharmacokinetics of levetiracetam. Epilepsia. 2001; 42(Suppl 4):24-27. 11564121
5. FDA Center for Drug Evaluation and Research (CDER), MedWatch Report, May 22, 2002.


Hiemke C, Baumann P, Bergemann N, et al. AGNP consensus guidelines for therapeutic drug monitoring in psychiatry: Update 2011. Pharmacopysychiatry. 2011 Sep; 44(6):195-235. 22053351


Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
716936 Levetiracetam (Keppra), S 30471-7 716937 Levetiracetam, S ug/mL 30471-7

For Providers

Please login to order a test.


© 2018  Laboratory Corporation of America® Holdings and Lexi-Comp Inc. All Rights Reserved.

CPT Statement/Profile Statement

The LOINC® codes are copyright © 1994-2018, Regenstrief Institute, Inc. and the Logical Observation Identifiers Names and Codes (LOINC) Committee. Permission is granted in perpetuity, without payment of license fees or royalties, to use, copy, or distribute the LOINC® codes for any commercial or non-commercial purpose, subject to the terms under the license agreement found at https://loinc.org/license/. Additional information regarding LOINC® codes can be found at LOINC.org, including the LOINC Manual, which can be downloaded at LOINC.org/downloads/files/LOINCManual.pdf