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Blood Test Tracker

Levetiracetam

Measures the level of levetiracetam, an anti-seizure medicine, in your blood to check it is being absorbed and cleared as expected.

AI-verified against cited sources. Awaiting expert reviewAlso called LEVLOINC 30471-7

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What it is

Levetiracetam (Keppra) is a prescription medicine that helps prevent seizures. About two-thirds of it leaves the body unchanged in the urine, so kidney function strongly affects the level. This test measures how much is in your blood, usually as a trough just before your next dose. Most people do not need regular level checks.

Why it matters

Levetiracetam has a wide safety margin, so its level is not needed to set the dose for most people. A level can help when seizures return, when your team wants to confirm you are taking it as planned, during pregnancy (when levels fall, most in the third trimester), in people with kidney disease or on dialysis, or after a suspected overdose.

If it’s low

A level below the reference range can mean doses were missed, the drug is being cleared faster than usual, or the sample was drawn a long time after the last dose. It is also common, since the lower end of the range is debated and many routine results fall near or under it. A low number does not by itself mean seizures will return, and your clinician reads it together with how you are doing.

Common causes

  • Missed or late doses
  • Pregnancy, when levels fall and the drop is largest in the third trimester
  • Dialysis shortly before the blood draw
  • Faster clearance in children and in people with strong kidney function
  • A sample drawn long after the last dose

What can help

  • Tell your care team about missed doses
  • Tell your care team if you are pregnant or planning a pregnancy, and ask whether levels should be checked
  • Check with your care team before changing or skipping any dose

If it’s high

A level above the reference range usually means the drug is clearing more slowly or the sample was drawn soon after a dose. Higher levels can add to side effects such as sleepiness, tiredness, dizziness, and changes in mood or behavior. Many people tolerate levels above the usual range, so your clinician looks at how you feel.

Common causes

  • Reduced kidney function, since most of the drug leaves through the kidneys
  • Older age, which often goes with lower kidney function
  • A sample drawn soon after a dose instead of just before the next one
  • Dehydration
  • Taking more than prescribed

What can help

  • Tell your care team about any kidney problems or recent illness
  • Ask whether your dose suits your kidney function
  • Check with your care team before changing or skipping any dose

Usual ranges

What labs print as the reference range, by who was tested. Ranges differ a little between labs, so the range on your own report is the one your result is judged against.

For adults: 10–40 mcg/mL. Source: ARUP Laboratories, Drugs in R&D, Drug Design, Development and Therapy, Clinical Pharmacology & Therapeutics.

What can affect your result

  • Kidney function (about 66% of the drug leaves unchanged in urine)
  • Pregnancy, with the largest drop in the third trimester
  • Dialysis
  • Age
  • Time since your last dose
  • How consistently you take your doses
  • The lab method (an immunoassay can cross-react with brivaracetam)
  • A sample drawn soon after a dose will read higher than a true trough.
  • Hemodialysis removes about half of the drug in 4 hours, so a level drawn after dialysis will be lower.
  • Some immunoassays for levetiracetam, including the one ARUP uses, cross-react with brivaracetam, so a result can be unreliable if you take both medicines. A chromatographic method tells them apart.

A trough, drawn just before your next dose, gives the most consistent comparison from one test to the next. About 2 days to settle at a new level after a dose change in people with normal kidney function (steady state is reached after 2 days of twice-daily dosing, per the FDA label). It takes longer with reduced kidney function.

When to talk to a clinician

Call your care team promptly if seizures become more frequent, or if you notice new or worsening low mood, strong irritability, unusual changes in behavior, or thoughts of harming yourself. Excess sleepiness or confusion is also worth a prompt call. If someone has a seizure that lasts longer than 5 minutes, has trouble breathing afterward, or you think there has been an overdose, call 911 or your local emergency number.

Questions you could ask

  • Do I need my levels checked regularly, or only when something changes?
  • How is my kidney function being monitored?
  • Could my kidney function be affecting my level?
  • Is my dose still right for me?
  • Could a missed dose, pregnancy or dialysis explain a low level?
  • Should we check my level again, and when?

Questions people ask

Do I need my levetiracetam level checked?

Usually not. Levetiracetam has a wide safety margin, and the dose is set by your seizures and side effects. Levels are most useful in pregnancy, kidney disease or dialysis, when seizures return, or to check that doses are being taken.

Why would my level drop during pregnancy?

The FDA label notes that levetiracetam levels fall during pregnancy, most in the third trimester, and may need adjusting. Levels are often rechecked after delivery. Talk with your care team early if you are pregnant or planning a pregnancy.

Why do different sources give different ranges?

Labs and experts have not agreed on one range. Some labs print 10 to 40 mcg/mL, an international group suggests 12 to 46, and Norwegian labs use 5 to 41. Because the drug is safe across a wide range, the number is mostly used to check that doses are being taken and to compare results over time.

Show the science and sources

Units

  • 1 mcg/mL = 1 mcg/mL
  • 1 mcg/mL = 1 mg/L
  • 1 mcg/mL = 5.875 µmol/L

Open the Levetiracetam unit converter

For clinicians and researchers

Levetiracetam is a pyrrolidone derivative with near-complete absorption, less than 10% protein binding and no cytochrome P450 metabolism. About 66% of a dose is excreted unchanged in urine, with an adult half-life of 7 ± 1 hours that lengthens with reduced renal function, and steady state is reached after about 2 days of twice-daily dosing. Printed ranges differ: ARUP lists 10 to 40 mcg/mL, a 2016 review suggests 12 to 46 mg/L for a daily dose of 1 to 3 g (the ILAE figure), and Norwegian labs use 5 to 41 mg/L; the ILAE lower limit rests on a retrospective database of highest doses, and about 45% of routine samples in two datasets were under 12 mg/L. A 2016 review also reports a roughly 60% drop in serum concentration in pregnancy. The label states that plasma concentrations decrease during pregnancy, most in the third trimester, and that hemodialysis removes about 50% in 4 hours. Concentration-effect relationships are weak. Some immunoassays (ARUP's uses ARK reagents) cross-react with brivaracetam. The 2017 AGNP consensus lists a laboratory alert level of 50 mcg/mL; only a handful of US hospitals include levetiracetam on critical lists.

LOINC 30471-7 (primary), 48347-9. Specimen: serum-or-plasma.

Sources

  1. An Updated Overview on Therapeutic Drug Monitoring of Recent Antiepileptic Drugs, Drugs in R&D (2016)
  2. KEPPRA (levetiracetam) tablets and oral solution: prescribing information, UCB, via DailyMed (NIH National Library of Medicine) (2026)
  3. Drug Critical Limits for Urgent Physician Notification, Clinical Pharmacology & Therapeutics (2026)
  4. Reference ranges for antiepileptic drugs revisited: a practical approach to establish national guidelines, Drug Design, Development and Therapy (2018)
  5. Keppra (Levetiracetam) (ARUP test 0098627), ARUP Laboratories

AI-verified against cited sources. Awaiting expert review. Last reviewed 2026-10-03. How we build and check these pages.

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