Phenytoin

This test measures the level of phenytoin in the blood, a medication used to control seizures in epilepsy. It helps ensure therapeutic levels are maintained.

Phenytoin has a narrow therapeutic range. Too little may cause seizures, while too much can lead to toxicity with symptoms like dizziness, confusion, and tremors.

It’s a blood test usually taken before the next scheduled dose (trough level) to get accurate readings.

It’s done regularly during treatment, especially when starting, adjusting doses, or if side effects or seizure control issues arise.

Factors include liver function, interactions with other drugs, age, nutritional status, and adherence to prescribed doses.