All tests · Therapeutic Drug Levels
Therapeutic Drug Levels
Normal range 10-20 µg/mL (40-79 µmol/L SI). Specimen: Serum (trough).
Also known as: Dilantin level.
Combined adult band. LabVals does not publish separate men's, women's, or pediatric ranges for Phenytoin Level; those can be narrower than the band shown.
| Specimen | Serum (trough) |
|---|---|
| Conventional range | 10-20 µg/mL |
| SI range | 40-79 µmol/L |
| Conversion factor | ×3.96 (conventional → SI) |
| Toxicity threshold | > 20 µg/mL (nystagmus, ataxia); > 30 confusion |
| Panel | Therapeutic Drug Levels |
Convert any Phenytoin Level result between units on the unit converter.
The standard teaching reference range for Phenytoin Level is 10-20 µg/mL in conventional units, or 40-79 µmol/L in SI units. This value is measured in serum (trough).
For Phenytoin Level, the commonly taught toxicity threshold is: > 20 µg/mL (nystagmus, ataxia); > 30 confusion.
Source: Adult reference values compiled from Pagana & Pagana, Mosby's Diagnostic and Laboratory Test Reference, and Fischbach & Dunning, A Manual of Laboratory and Diagnostic Tests. Reference ranges vary by laboratory, method, age, sex, and population - always use the range printed on the actual result.
Above the range
Below the range
At the bedside
You have the Phenytoin Level range. Premium unlocks the 9-card Therapeutic Drug Levels flashcard deck with mastery tracking, study sheets that put several panels on one printable page, and unlimited practice across all 440 quiz questions - the free round stops at 10 a day.
Same panel