{"id":"lamotrigine","name":"Lamotrigine","shortName":"Lamotrigine","aliases":["Lamictal","Lamotrigine Level","Lamotrigine, Serum","LTG","Lamotrigine, Serum or Plasma","Lamotrigine Serum Level","Lamotrigine Blood Level","Lamictal Level","Lamotrigine (Lamictal)"],"abbreviations":["LTG"],"loinc":[{"code":"6948-4","primary":true},{"code":"25458-1","primary":false},{"code":"74944-0","primary":false}],"specimen":"serum-or-plasma","units":[{"ucum":"ug/mL","display":"mcg/mL"},{"ucum":"mg/L","display":"mg/L"},{"ucum":"umol/L","display":"µmol/L"}],"referenceRanges":[{"population":"Adults","low":3,"high":15,"unit":"ug/mL","unitDisplay":"mcg/mL","note":"ARUP lists a therapeutic range of 3 to 15 mcg/mL, and a 2016 review of antiepileptic drug monitoring gives 2.5 to 15 mg/L (the same units). A 2018 review found labs in Norway use 3 to 13 or 3 to 15 mg/L, and the ILAE recommends 3 to 15. The FDA label says a therapeutic range has not been established and that dosing should follow response, so treat this as a guide, not a goal. Many people do well outside it. ARUP lists levels of 20 mcg/mL or higher as toxic. Guidelines for bipolar disorder in England advise measuring levels only for ineffectiveness, poor adherence or toxicity.","sources":[{"title":"Lamotrigine (ARUP test 0090177)","url":"https://ltd.aruplab.com/Tests/Pub/0090177","publisher":"ARUP Laboratories"},{"title":"An Updated Overview on Therapeutic Drug Monitoring of Recent Antiepileptic Drugs","url":"https://doi.org/10.1007/s40268-016-0148-6","publisher":"Drugs in R&D","year":2016},{"title":"Reference ranges for antiepileptic drugs revisited: a practical approach to establish national guidelines","url":"https://doi.org/10.2147/dddt.s154388","publisher":"Drug Design, Development and Therapy","year":2018},{"title":"LAMICTAL (lamotrigine) tablets: prescribing information","url":"https://dailymed.nlm.nih.gov/dailymed/lookup.cfm?setid=d7e3572d-56fe-4727-2bb4-013ccca22678","publisher":"GlaxoSmithKline, via DailyMed (NIH National Library of Medicine)","year":2025},{"title":"Bipolar disorder: assessment and management (CG185), recommendations","url":"https://www.nice.org.uk/guidance/cg185/chapter/Recommendations","publisher":"National Institute for Health and Care Excellence (NICE)","year":2014}]}],"review":{"status":"ai-verified","label":"AI-verified against cited sources. Awaiting expert review","lastReviewed":"2026-10-03"},"summary":"Measures the level of lamotrigine, a seizure and mood medicine, in your blood to check it is being absorbed and cleared as expected.","url":"https://bloodtesttracker.com/markers/lamotrigine","notice":"Information, not medical advice. Ranges differ between labs, so the range on your own report is the one your result is judged against."}