What is this test?
This test checks the level of the seizure medicine phenytoin (Dilantin) in your blood. Phenytoin is an anticonvulsant medicine given to control seizures.
Why do I need this test?
You may need this test if you take phenytoin. Your healthcare provider must check your blood to make sure you are getting the correct dose. Too much can be toxic. Not enough leaves your seizures uncontrolled.
You may have this test more often when you first start taking the medicine and then regularly throughout treatment. You may need to repeat the test if the medicine doesn't seem to control your seizures or if any of your other prescription medicines change.