Levetiracetam Serum Test: Uses, Range & Symptoms

Overview

The Levetiracetam Serum Test is a blood test that measures the amount (concentration) of levetiracetam present in the bloodstream. Levetiracetam is an anti-seizure (antiepileptic) medication, commonly known by the brand name Keppra. Doctors prescribe it to treat conditions like epilepsy, seizure disorders, and sometimes seizures caused by brain injury, infections, or surgeries.

The goal of this test is to ensure that the drug level in the body stays within a therapeutic range—meaning high enough to prevent seizures but not so high that it causes side effects or toxicity. Since people metabolize drugs differently, measuring the blood level helps doctors personalize the dose for safe and effective treatment.

This test is especially useful for people who are:

• Starting levetiracetam treatment
• Not responding well to the current dose
• Experiencing side effects
• Pregnant
• Elderly
• Living with kidney problems
• Taking multiple medications

Is Levetiracetam Produced in the Body?

No. Levetiracetam is not naturally made by the body. It is a synthetic drug that must be taken:

• By mouth (tablet, liquid)
• Through an intravenous (IV) injection in hospitals

After the medicine is taken:

1. It is absorbed in the small intestine
2. It enters the bloodstream
3. A small portion is metabolized
4. Most of it is removed from the body by the kidneys

Because the kidneys play a major role in clearing levetiracetam, people with kidney problems may retain higher levels in their blood, which increases the risk of side effects. That’s why this test is important in such patients.

Why Is the Levetiracetam Serum Test Important?

This test helps in several key areas:

1. Checks if the Dose Is Correct

The right level ensures the medicine is working effectively.

2. Improves Seizure Control

If the drug level is too low, seizures may continue or worsen.

3. Prevents Toxicity

High levels can cause side effects like confusion, extreme drowsiness, and behavioral changes.

4. Helps Adjust Doses

Doctors may adjust the dose based on:

• Age
• Kidney function
• Pregnancy
• Other medications
• Weight changes

5. Useful When Symptoms Don’t Match Expectations

For example:

• The patient is taking the medicine but still having seizures
• The patient is unusually sleepy or confused
• Sudden behavior or mood changes occur

Causes of Low Levetiracetam Levels

Low drug levels in the blood may happen due to:

• Missing doses or irregular intake
• Taking a lower dose than needed
• Rapid clearance by the kidneys
• Drug interactions that increase metabolism
• Incorrect prescription or dosing schedule
• Vomiting or malabsorption

Symptoms of Low Levels

When the drug is too low, seizures may not be controlled. Symptoms include:

• More frequent seizures
• Breakthrough seizures despite medication
• Unpredictable seizure episodes
• Worsening seizure intensity

Low levels do NOT cause their own physical symptoms—it’s the return of seizures that signals a problem.

Causes of High Levetiracetam Levels

High levels may occur if:

• The dose is too high
• There is kidney impairment
• The medication is taken too often
• Drug interactions reduce clearance
• The patient takes an accidental overdose

Symptoms of High Levels

High levels may cause:

• Drowsiness or dizziness
• Confusion or disorientation
• Headache
• Irritability or aggression
• Mood swings
• Behavioral changes
• Agitation
• Coordination problems

Severe toxicity may cause:

• Breathing difficulty
• Loss of consciousness
• Extreme sleepiness
• Coma (rare)

If such symptoms appear, medical attention is needed immediately.

Reference / Therapeutic Range

Typical target range:

• 12–46 µg/mL

This may vary slightly between laboratories.

• Below 12 µg/mL → May be too low to control seizures
• Above 46 µg/mL → Higher risk of toxicity or side effects

Doctors may repeat the test to confirm the level or adjust the dose accordingly.

Sample Type and Timing

• The test uses a serum (blood) sample.
• Blood is usually drawn from a vein in the arm.

Ideal Timing

The sample is often taken just before the next dose, known as a:

Trough level

This gives the most accurate measure of how low the drug level gets between doses.

Who Needs This Test?

A doctor may recommend this test if:

• You’re starting levetiracetam therapy
• Seizures are not well controlled
• You’re having unusual side effects
• You’re pregnant (drug levels can change)
• You’re elderly or have kidney disease
• You’re taking multiple medications
• You missed doses or overdosed
• You’re switching from another seizure medication

It may also be done in emergency situations, such as suspected overdose.

Other Tests That May Be Done Alongside

• Kidney function tests (creatinine, eGFR)
• Liver tests
• EEG (brain activity test)
• Blood levels of other seizure medications (if taking multiple drugs)

Test Preparation

• Usually no fasting is needed.
• Take the medication as instructed unless the doctor advises otherwise.
• Inform the doctor if:
  • You missed recent doses
  • You have kidney issues
  • You are pregnant or breastfeeding
  • You take other medications, including herbal or OTC drugs

When to Consult a Doctor

Seek medical advice if:

• Seizures increase or return
• You experience major mood or behavior changes
• You feel excessively sleepy or confused
• You have kidney disease and notice new symptoms
• You miss multiple doses
• You suspect overdose

Urgent care is needed if:

• You faint
• You have trouble breathing
• The person is unresponsive

Important Word Explanations

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