To determine the concentration of levetiracetam in the blood to establish an individualized dose; to detect toxicity or verify that you are taking the medication as prescribed (compliance); to monitor during health changes that may affect drug clearance and/or kidney function
Initially when establishing dosage; when indicated to detect low or excessive (potentially toxic) concentrations; when you have decreased kidney function; sometimes to verify compliance
A blood sample drawn from a vein in your arm, typically just before your next dose
Levetiracetam is a drug that is used to treat certain seizure disorders (epilepsy) such as: juvenile myoclonic epilepsy, temporal lobe epilepsy, complex partial seizures, myoclonic seizures, refractory seizures, secondarily generalized seizures, simple partial seizures, tonic-clonic seizures. The drug is prescribed as a secondary (adjunctive) treatment in combination with other antiepileptic drugs. This test measures the amount of levetiracetam in the blood.
Epilepsy affects the brain's ability to transmit electrical impulses and to regulate nerve activity. During a seizure, a person may experience changes in consciousness, alterations in sight, smell, and taste, and may experience convulsions. The frequency of seizures varies from a single episode, to occasional seizures, to recurrent seizures. Seizures are categorized by the parts of the brain and body that are affected. Levetiracetam is prescribed to help prevent specific types of recurrent seizures.
Levetiracetam is one of several newer second-generation antiepileptic drugs. It has a wider therapeutic range than many existing first-generation seizure medications. That is, the range of concentration in the blood in which the drug is effective without being toxic is broader, making it somewhat safer. It is also associated with fewer severe side effects and does not interact with as many other drugs. Levetiracetam provides a combination of efficacy and safety that is superior to other treatment choices in many clinical circumstances.
Because levetiracetam has a wider therapeutic range, it does not need to be monitored in the same manner as first-generation antiepileptic drugs. (For further discussion of this, see the article on Therapeutic Drug Monitoring.)
At the start of therapy, doses of levetiracetam may be gradually increased until a standard amount is reached. Once a stable dose is achieved, a blood level may be measured to ensure that it is within the therapeutic range. Since levetiracetam is an adjunct (secondary) medication, the healthcare practitioner will consider the effectiveness of both drugs that are prescribed and adjust them as necessary.
How is the sample collected for testing?
A blood sample is obtained by inserting a needle into a vein in the arm.
Is any test preparation needed to ensure the quality of the sample?
No test preparation is needed.
How is it used?
This test is used to measure the amount of levetiracetam in the blood to determine whether the level of drug is within the therapeutic range. Initially, the test may be ordered to help establish the appropriate dose for an individual. Since the therapeutic range is relatively wide and not well established, the healthcare practitioner will evaluate the effectiveness of the dose in controlling seizures and the presence and severity of side effects in the individual. Depending on these clinical findings and the results of the blood test, the dose of drug may be adjusted up or down.
Routine periodic monitoring of levetiracetam is usually not required. However, there are circumstances in which it is useful and sometimes necessary to measure blood levels. Some of these include:
- To establish the range that is therapeutic for an individual (dose individualization); after treatment has started and the individual has relief from symptoms (no seizures) and suffers no side effects, the concentration of the drug in the blood is determined. The range around this value is considered therapeutic for the person and may be used to evaluate that person's treatment in the future if the person's health status or other factors change.
- To verify that a person's symptoms (seizures or side effects) are not due to too little or too much drug; to verify that a person is taking the medication as prescribed
- To evaluate and adjust the dose as necessary in certain conditions such as:
- Kidney disease—levetiracetam is cleared from the body by the kidneys, so anything that affects kidney function can affect blood levels of the drug.
- A change or addition of other drugs
- Aging—people typically are prescribed seizure medications for life and, as they age, the amount of drug needed to be effective may change.
- Pregnancy—this condition can temporarily affect drug metabolism and clearance.
A healthcare practitioner may use a levetiracetam test to help evaluate someone who is experiencing side effects or adverse reactions or experiencing a recurrence of seizures or symptoms. In some cases, testing may be ordered to verify that the person is taking the medication as prescribed (compliance).
When is it ordered?
Levetiracetam tests may occasionally be ordered after a person begins taking the drug and a stable dose is achieved. Additional levetiracetam tests may be ordered when dosages of the drug are changed and sometimes when the treated person starts or stops taking additional medications in order to judge their effect, if any, on the levetiracetam level.
Tests may be ordered periodically when a person has decreased kidney function, has an underlying condition that may affect kidney function, and/or has significant liver dysfunction.
It may be ordered when a person does not appear to be responding to therapy and has a recurrence of seizures. The blood level may not be high enough, the person may not be taking the medication as prescribed, or the drug may be ineffective for that person.
Levetiracetam tests may also be ordered when a person experiences a troublesome level of side effects and/or develops complications. Side effects that may be seen at any dose but that are related to higher concentrations include:
- Lack of coordination
- Loss of appetite
- Memory problems
- Numbness, tingling, or burning in the hands or feet
- Thoughts of suicide
People who take levetiracetam should talk to their healthcare practitioner about the timing of the sample collection. Often, the recommended time is just before the next dose is taken (trough level).
What does the test result mean?
The therapeutic range for levetiracetam is about 12.0 - 46.0 mcg/mL (mg/L). Levels above 46 mcg/mL are considered potentially toxic. Ranges vary slightly from laboratory to laboratory. Healthcare practitioners and people tested should use the therapeutic ranges and units established by the laboratory that performs the testing. Toxic levels have not been well established. Therapeutic ranges are based on the specimen immediately before the next dose (trough levels).
Within the therapeutic range, most people will respond to the drug without excessive side effects; however, response varies with each individual. Some people will experience seizures at the low end of the therapeutic range, some will experience excessive side effects at the upper end, and some will require dosages outside of the established range for effectiveness and/or freedom from side effects. People who use this medication should work closely with their healthcare practitioner to find the dosage that works the best for them.
In general, if levetiracetam test results are within the therapeutic range (or at an individually established level) and the treated person is not having recurrent seizures and is not experiencing significant side effects, then the drug dosage is considered adequate.
A level that is outside the therapeutic range may mean an individual is not taking the drug as prescribed. This is important to know since this may put the person at increased risk of experiencing symptoms.
Is there anything else I should know?
How long will I need to be on levetiracetam?
People who have epilepsy will typically take levetiracetam or other medications throughout their lifetime. If levetiracetam ceases to be effective or causes adverse effects, then the person may need to be given different drug(s).
Can I test my levetiracetam level at my healthcare practitioner's office?
What other antiepileptic drugs (AEDs) are there?
There are a broad range of AEDs available that have different forms of action and are used to treat different types of seizures. First-generation AEDs that have been use for a long period of time include: phenobarbital (since the early 1900s), phenytoin, carbamazepine, ethosuximide, and valproate (valproic acid). Newer, second-generation AEDs include drugs such as: gabapentin, lamotrigine, oxcarbazepine, topiramate, and levetiracetam. Some of these are used by themselves, but most of the newer AEDs are used in combination with other drugs.
On This Site
Elsewhere On The Web
MedlinePlus Drug Information: Levetiracetam
Epilepsy Foundation: About Epilepsy, The Basics
Epilepsy Foundation: Seizure and Epilepsy Medicines
American Epilepsy Foundation: About Epilepsy