The Test Sample
What is being tested?
Levetiracetam is a drug that is used to treat certain seizure disorders (also called epilepsy). It is prescribed as an adjunctive (secondary) 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. Since it is relatively new, however, it has less of a use history – its long-term safety and efficacy and its appropriate therapeutic range are less well established.
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.) 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; 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 their treatment in the future if their 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.
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 doctor 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.
NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
Is any test preparation needed to ensure the quality of the sample?
No test preparation is needed.