Sign in →

EPIC CODE: LAB475 Lamotrigine, Serum

Additional Codes

Sunquest:  LAMOTM
Mayo:         LAMO
Previously: ARUP 0090177 

Reporting Name

Lamotrigine, S

Useful For

Monitoring serum concentration of lamotrigine


Assessing compliance


Adjusting lamotrigine dose in patients receiving other anticonvulsant drugs that interact pharmacokinetically with lamotrigine

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Specimen Type


Specimen Required

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. Centrifuge within 2 hours of collection

4. For red-top tubes, immediately aliquot serum into a plastic vial.

5. For serum gel tubes, aliquot serum into a plastic vial within 24 hours of collection.

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

Reference Values

Patients receiving therapeutic doses usually have lamotrigine concentrations of 3.0-15.0 mcg/mL.

Day(s) Performed

Monday through Sunday

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 US Food and Drug Administration.

CPT Code Information


LOINC Code Information

Test ID Test Order Name Order LOINC Value
LAMO Lamotrigine, S 6948-4


Result ID Test Result Name Result LOINC Value
80999 Lamotrigine, S 6948-4

Clinical Information

Lamotrigine (Lamictal) is approved for therapy of bipolar I disorder and a wide variety of seizure disorders including Lennox-Gastaut syndrome, primary generalized tonic-clonic seizures, and partial seizures. Its many off-label uses include treatment of migraine, trigeminal neuralgia, and treatment-refractory depression. Lamotrigine inhibits glutamate release (an excitatory amino acid) and voltage-sensitive sodium channels to stabilize neuronal membranes; it also weakly inhibits the 5-HT3 (serotonin) receptor.


Lamotrigine oral bioavailability is very high (approximately 98%). The drug is metabolized by glucuronic acid conjugation to inactive metabolites. The half-life is 25 to 33 hours in adults but decreases with concurrent use of phenytoin or carbamazepine (13-14 hours) and increases with concomitant valproic acid therapy (59-70 hours), kidney dysfunction, or hepatic impairment. The therapeutic range is relatively wide, 3 to 15 mcg/mL for most individuals. Common adverse effects are dizziness, ataxia, blurred or double vision, nausea, or vomiting.


The serum concentration should be interpreted in the context of the patient's clinical response and may provide useful information in patients showing poor response, noncompliance, or adverse effects, particularly when lamotrigine is coadministered with other anticonvulsant drugs.


While most patients show response to the drug when the trough concentration is in the range of 3.0 to 15.0 mcg/mL and show signs of toxicity when the peak serum concentration is greater than 20 mcg/mL, some patients can tolerate peak concentrations as high as 70 mcg/mL.


Serum separator tube is acceptable but serum should be removed from gel within 24 hours of collection.

Clinical Reference

1. Rifai N, Horvath AR, Wittwer CT, eds. Tietz Textbook of Clinical Chemistry and Molecular Diagnostics 6th ed. Elsevier; 2018

2. Johannessen SI, Battino D, Berry DJ, et al: Therapeutic drug monitoring of the newer antiepileptic drugs. Ther Drug Monit. 2003 Jun;25(3):347-363. doi: 10.1097/00007691-200306000-00016

3. Johannessen SI, Landmark CJ: Value of therapeutic drug monitoring in epilepsy. Expert Rev Neurother. 2008 Jun;8(6):929-939. doi: 10.1586/14737175.8.6.929

4. Johannessen SI, Tomson T: Pharmacokinetic variability of newer antiepileptic drugs: When is monitoring needed? Clin Pharmacokinet. 2006;45(11):1061-1075. doi: 10.2165/00003088-200645110-00002

5. Physician's Desk Reference. 71st ed. Thomson PDR; 2017

6. Hardman JG, Limbird LE, Gilman AG, eds. Goodman and Gilman's The Pharmacological Basis of Therapeutics. 10th ed. McGraw-Hill Book Company; 2001

7. Hiemke C, Bergemann N, Clement HW, et al: Consensus guidelines for therapeutic drug monitoring in neuropsychopharmacology: Update 2017. Pharmacopsychiatry. 2018 Jan;51(1-02):9-62. doi: 10.1055/s-0043-116492

Method Description

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

Report Available

Same day/1 to 2 days

Specimen Retention Time

14 days

Reject Due To

Gross hemolysis OK
Gross lipemia OK
Gross icterus OK

NY State Approved


Method Name

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


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

-Neurology Specialty Testing Client Test Request (T732)

-General Request (T239)

-Therapeutics Test Request (T831)

Secondary ID