Phenytoin, Free [3189X]

Test Code

23692

CPT Codes
80186

Preferred Specimen

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

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

Minimum Volume

1 mL

Transport Container

Plastic screw-cap vial

Transport Temperature

Room temperature

Specimen Stability

Room temperature: 4 days
Refrigerated: 7 days
Frozen: 30 days

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

Specimen received in serum separator tube (SST) • Plasma

Methodology
Ultrafiltration/Immunoassay

Setup Schedule

Set up: Mon-Sat a.m.; Report available: Next day

Reference Range

1.0-2.0 mg/L

Clinical Significance

Phenytoin is used singly or in combination with other anticonvulsants to treat grand mal epilepsy. Monitoring the serum levels of antiepileptic drugs has increased the efficiency and safety of drug therapy in epilepsy. It facilitates individualization of

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.