The Client Has Epilepsy, and Receives Phenytoin (Dilantin)

The client has epilepsy, and receives phenytoin (Dilantin) .The client has been seizure-free, and asks the nurse why he still needs blood tests when he is not having seizures.The nurse is aware the phenytoin (Dilantin) can:

A) Deplete potassium.
B) Cause Steven-Johnson syndrome.
C) Have a narrow range between a therapeutic dose and a toxic dose.
D) Cause blood thinning in some clients.