Hello, There is no need for blood test dilantin level if one isn t taking Dilantin, it is done to check if it is in therapeutic levels in those under therapy. However, what is more, important in this case is to understand what steps have been taken to search for the cause of the seizure. A first time seizure at this age should be carefully investigated for its origin. It may be in the setting of a stroke or a brain tumor for which reason brain imaging preferably by MRI is recommended. It can also be due to metabolic alterations, infection or inflammation, to investigate in that regard some routine blood tests are needed as well. An EEG is also needed to control brain electrical activity for epileptiform discharges. These tests are more important than starting an antiepileptic as if a cause is identified that should be addressed first. If all results normal and no cause is found then it is the question of the preventive antiepileptic medication. It is a debated issue, but if it was only one single isolated seizure and no cause could be identified then generally it is recommended to wait, not to initiate treatment with one isolated seizure. While about many people about 10% of people can have seizures during their lifetime, only less then 3% develop epilepsy, having repeated seizures. In many seizures do not repeat or it may not have been a seizure at all but a syncope or psychogenic. So generally it is preferred to wait and not start treatment for an isolated seizure. If there has been more than one seizure treatment is initiated, dilantin is one common option but there are many others, the choice depends on type of seizures, imaging and EEG findings. Hope I have answered your query. Let me know if I can assist you further. Take care Regards, Dr. Olsi Taka, Neurologist