The Phenytoin level looks at amount of phenytoin in blood. It is done for: seizure control and toxicity.
General health information, not a diagnosis. In an emergency, call 102. Always consult a qualified health professional.
Seizure control and toxicity.
Trough sample before the next dose. Laboratory-specific; see the reference range on your report. High or positive may mean: Toxicity risk (unsteadiness). Low or negative may mean: May not prevent seizures. General information, not a diagnosis. Results must be interpreted by a qualified health worker.
Amount of phenytoin in blood.
Blood
Toxicity risk (unsteadiness).
May not prevent seizures.
Reference ranges vary by lab, age and sex — always use the range printed on your own report.
Consult a doctor to interpret results — a single test does not make a diagnosis.
Uses your location once to list the nearest facilities. Nothing is stored.
What does the Phenytoin level measure?
Amount of phenytoin in blood.
Why is the Phenytoin level done?
Seizure control and toxicity.
Do I need to fast for the Phenytoin level?
Trough sample before the next dose.
What does a high or positive Phenytoin level mean?
Toxicity risk (unsteadiness).
What does a low or negative Phenytoin level mean?
May not prevent seizures.
What is the normal range for the Phenytoin level?
Laboratory-specific; see the reference range on your report.
Why is Phenytoin level done?
Seizure control and toxicity.
Do I need to prepare or fast for Phenytoin level?
Trough sample before the next dose. Laboratory-specific; see the reference range on your report. High or positive may mean: Toxicity risk (unsteadiness). Low or negative may mean: May not prevent seizures. General information, not a diagnosis. Results must be interpreted by a qualified health worker.
SI text CC BY 4.0; decoder reference data (cited per range); LOINC codes free with attribution (notice included).
Sources: SI health summary (own words); MedlinePlus Lab Tests and CDC as references