Phenytoin

Test Code

713

CPT Codes
80185

Preferred Specimen

1 mL serum collected in a red-top tube (no gel)

Minimum Volume

0.2 mL

Other Acceptable Specimens

Plasma collected in: Sodium heparin (green-top) tube, lithium heparin (green-top) tube, or EDTA (lavender-top) tube

Instructions

Collect as trough just prior to next dose. For patients receiving fosphenytoin therapy, collect as trough at least 2 hours after IV infusion or at least 4 hours after IM injection.

Transport Temperature

Room temperature

Specimen Stability

Room temperature: 5 days
Refrigerated: 10 days
Frozen: 30 days

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)

Serum separator tube (SST)

Methodology
Immunoassay (IA)

Setup Schedule

Set up: Mon-Thurs p.m., Fri, Sat evenings; Report available: Next day

Reference Range

10.0-20.0 mg/L

Clinical Significance

Phenytoin is an anticonvulsant hydantoin used for the treatment of generalized tonic-clonic (grand mal) and complex partial seizures. Phenytoin is also used for prophylaxis in neurosurgical procedures. Phenytoin levels are monitored to assure adequate therapeutic levels are achieved and to avoid toxicity.

Performing Laboratory
Quest Diagnostics Nichols Institute
14225 Newbrook Drive
Chantilly, VA 20153

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.