PHENYTOIN (DILANTIN®), FREE, SERUM

Additional Codes

Software	Test Code
Label Text	FPHNY
EPIC	LAB32

Performing Laboratory

NorDx Laboratories

Useful For

Monitoring phenytoin levels

Phenytoin is the drug of choice to treat and prevent tonic-clonic and psychomotor seizures. If phenytoin alone will not prevent seizure activity, co-administration with phenobarbital is usually effective.

Method Name

Spectrophotometry (SP)

Reference Values

Therapeutic concentration: 1.2-2.5 ug/mL

Toxic concentration: > 3.0 ug/mL

Free PHENYTOIN levels should be drawn as a trough (2 hours prior to the next scheduled dose) after 3-4 days of therapy to ensure steady state is achieved, unless there is concern for toxicity in which case levels can be checked anytime. Free PHENYTOIN concentration is recommended in patients with uremia, hypoalbuminemia, hyperbilirubinemia, hepatic impairment or concomitant medicactions that may displace PHENYTOIN from its albumin binding sites

Days and Times Test Performed

Monday through Sunday

Report Available

1 Day

Available Stat

Specimen Type

Serum

Preferred Container

Red Top Tube

Preferred Volume

Serum: 2 mL (Red Top Tube)

Minimum Volume

Serum: 1 mL (Red Top Tube)

Specimen Collection and Handling

1. Spin specimen, separate from clot and send refrigerated.

2. Fosphenytoin and phenytoin levels are best measured as a trough level, with specimen collection being performed 2 hours PRIOR to the next dose.

Specimen Stability Information

Specimen Type: Serum

Frozen: 3 Months

Refrigerated: 6 Days

Must be spun/separated within: 2 Hours

Add On Capable

Yes

Advance Beneficiary Notice Requirements

No ABN Required

CPT Code Information

CPT Code	CPT Description	CPT Disclaimer
80186	Drug Screen Quantitative Phenytoin, Free

Keywords

DILANTIN® (PHENYTOIN)

DIPHENYLHYDANTOIN

FREE DILANTIN® (PHENYTOIN)

PHENYTOIN (DILANTIN®)

Performing Laboratory Location