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Normal Dilantin level and still had a seizure



My brother just had a grand-mal seizure and his Dilantin level was normal. How can this happen? We were told as long as he takes his medicine on time to keep his level normal, he shouldn`t have a seizure, he takes 400mg a day. Also, he has a pattern over the last 15 years that a seizure will come 4 hours after he wakes. This seizure was so different, because it was longer then the usual 4 hours and his level was normal. Please Help! Thanks!


The Dilantin level is the amount of medication in the bloodstream. The laboratory gives us a `normal` range when they report the results of the blood test. The range for Dilantin is between 10 and 20. However, having a blood level in this range does not guarantee that seizures will be controlled. The range was developed from a large population of patients whose seizures were controlled. Remember the blood levels are only a guide for the treating physician and it is still possible to have a seizure when the blood level is the `normal range.`

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Response by:

David M Ficker, MD David M Ficker, MD
Associate Professor
College of Medicine
University of Cincinnati