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 doctor 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 is usually not required, but levetiracetam tests may be ordered to adjust the dosage as necessary if the treated person becomes pregnant or if there is a health change, a decrease in kidney function, or any other condition that may affect the rate of clearance of the drug. In some cases, a levetiracetam test may be ordered if someone begins taking other drugs in order to determine whether an adjustment to the prescribed dose is necessary.
A doctor 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).
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
Numbness, tingling, or burning in the hands or feet
Thoughts of suicide
People who take levetiracetam should talk to their doctor about the timing of the sample collection. Often, the recommended time is just before the next dose is taken (trough level).
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. Doctors and people tested should use the therapeutic ranges and units established by the laboratory that performs the testing.
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 doctor 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 by the doctor. This is important to know, as this may put the person at increased risk of experiencing symptoms.
This article was last reviewed on May 31, 2013. | This article was last modified on May 31, 2013.
The review date indicates when the article was last reviewed from beginning to end to ensure that it reflects the most current science. A review may not require any modifications to the article, so the two dates may not always agree.
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