A 29-year-old woman comes to the clinic for routine follow-up. | Uworld | Step 2ck

A 29-year-old woman comes to the clinic for routine follow-up. Five years ago, she experienced an unprovoked generalized tonic-clonic seizure. At that time, phenytoin was prescribed, and the patient has been on a stable dose since. She has not experienced seizure recurrence. MRI of the brain performed following the initial episode was normal. She has no other medical problems and is a lifetime nonsmoker. The patient's family history is negative for neurologic disease. She is in a stable relationship and is contemplating pregnancy. Blood pressure is 123/72 mm Hg and pulse is 75/min. Neurologic examination is unremarkable. Serum phenytoin level is 11 mcg/ml (therapeutic range, 10-20 mcg/ml}. Electroencephalogram is normal.