Phenytoin (Dilantin), Free Blood Test
Test Code: 070763
Specimen Type: Blood
Phenytoin (Dilantin), Free Blood Test (Labcorp)
This test measures levels of Free or unbound Phenytoin in the blood. Phenytoin is an anticonvulsant drug that is prescribed to help treat or prevent certain types of seizures. It is commonly sold under the brand name Dilantin. Phenytoin must be taken at the proper dosage to be effective. However, taking too much can cause toxicity with symptoms including loss of balance, eye twitching, confusion, shaking, low blood pressure, and slurred speech. Free Phenytoin is the portion of the drug that is biologically active and mot bound to proteins in the blood. For people with certain health conditions measuring the level of free phenytoin may be more accurate than a standard total phenytoin test. Conditions such as kidney failure, liver disease, or abnormally low albumin levels can cause higher than usual levels of free phenytoin even though total phenytoin levels appear normal. This can lead to toxicity if the person's dosage is not adjusted accordingly.
Phenytoin testing is typically ordered when someone is taking phenytoin and has a condition known to increase free phenytoin levels. It may also be done when someone is showing normal levels on a total phenytoin test but is experiencing symptoms of toxicity. Results should always be reviewed with a person's prescribing physician.
Turnaround for this test is typically 3-5 business days.
Where can I find a Phenytoin (Dilantin), Free Blood Test near me?
Check our lab finder to locate a collection site in your area.
Note: Result turn around times are an estimate and are not guaranteed. Our reference lab may need additional time due to weather, holidays, confirmation/repeat testing, or equipment maintenance.
It is typically recommended that the specimen for this test be collected shortly before taking your next dose. Consult your doctor to determine optimal specimen collection time.