What is analysed?

Phenytoin is a medication used to treat and prevent seizures in patients who have epilepsy. The phenytoin test analyses levels of phenytoin in the blood.

What does the result mean?

The result indicates the concentration of phenytoin in the blood.

Why conduct the analysis?

The phenytoin test is conducted to monitor and maintain optimal therapeutic levels of phenytoin. Deviations from the therapeutic range may lead to phenytoin toxicity and inadequate seizure control.

When to conduct the analysis?

The phenytoin test is conducted:

• Regularly, to monitor the effectiveness of treatment.

• Specifically, when signs of low or toxic phenytoin concentrations are observed.

What sample is required?

A blood sample is required. The blood is taken from a vein, usually in the arm.

Is any prior preparation necessary?

Patients should fast for 12 hours before the sample is taken. In addition, patients should inform a healthcare professional about any medications being taken, as these could affect results

How is it performed?

The sample is sent to a laboratory, where it is analysed using immunoassays or high-performance liquid chromatography (HPLC) methods to quantify the amount of phenytoin in the blood.

What are the normal values?

What does having altered values mean?

• High phenytoin levels: Indicate phenytoin toxicity. Dosage reduction or discontinuation are required.
• Low phenytoin levels: Can result in inadequate seizure control. Dosage increase or consideration of alternative medications are required.